General Changes:
-Focus attacks are faster.
-Ten brand new characters! Juri and Hakan are brand new, while Cody, Guy, Ibuki, Makoto, Dudley, Adon, DeeJay and T. Hawk all return for another round!
-Not DLC. The game will be shipped on a physical disc.
-Will cost $40 USD!
-Brand new opening and closing videos for each character in an anime format.
-Not compatible with SF4 for online matches.
-Some 'bonus' for keeping your original SF4 disc. DLC costumes?
-Each returning character has three costumes confirmed. Will there be more? DLC, unlockable, require SF4 disc?
-Reworking of the online code.
-A team battle mode has been added. Up to 8 players are put into a room and divided into teams based on points. It's possible to have a 7v1 in this set-up!
-An 8 player "Endless Battle" online mode has been added. Players not fighting can spectate and comment via voice chat. No points are won/loss in this mode.
-Replays can always be saved.
-Replay channels have been added to watch and discuss matches with others.
-A tournament mode will be added later as DLC. Will allow 8 players, voice chat, save replays (even one's that you didn't play in), and offer titles for the winners.
-Each character has two Ultra's now and are selected before a match begins.
-Roster unlocked from start. No unlocking required.
-All online modes will have blind select. The cursor sound has been removed as well.
-New intro song.
-Shipping April 28, 2010.

New Characters:
Adon
950 stamina, 1000 stun.
Seems weak.
Very good overhead.
Jaguar Tooth and Kick unsafe on block.
Jaguar Kick breaks armor.

Cody
1000 stamina, 1050 stun.
Can FADC Tornado Uppercut after first hit, cannot cancel it into ultra.
Zonk Knuckle currently annoying and good. Three levels of charge.
He has a knife. It increases attack damage and makes normals deal chip.
Ultra 1: Final Destruction: Series of punches ending in a tornado uppercut.
Ultra 2: Last Dread Dust: Ultra that we've seen in the videos multiple times

Dee Jay
1000 stamina, 1000 stun.
Decent?
Very fast.
Many easily executed combos.
Good crossups.
Machine Gun Upper is a charge move, no longer requires mash.
Ultra 1: Sobat Festival - Charge bfbf + KKK. This is the one you've seen in the videos a lot.
Ultra 2: Climax Beat - done like Guile's current Ultra move in SF4

Dudley
1050 stamina, 1050 stun.
Corkscrew Cross can connect with airborne opponents, so it's better for combos. Rolling Thunder meanwhile does not (fully?) connect with airborne opponents, but does more damage to compensate.
gun upper FADC ultra works
Rolling Thunder goes through projectiles

Guy
950 stamina, 1000 stun.
Chain combos into super.
EX Spin Kick is vertical
EX Shoulder is best move, super fast.
Ultra 1: Muso Renge - Grab ultra. Not heavy on the damage, but coupled with his speed, a grab Ultra could be pretty darn good.

Hakan
1050 stamina, 1100 stun.
Oils up (srk + k) which increases throw ranges and damage. Increases oil time based on kick used. EX does ?
Has a coward crouch (like Blanka)
Two command grabs, one SPD motion that shoots the opponent out of his arms, and another ddt like one.
Slide move is armor breaking.
Ultra 1 is trap like. Lies on belly and blah blah blah. Cannot do ANYTHING. Walk, touch, attack. He will get you.
Ultra 2 is the Oil Coaster. Yaaaay.

Ibuki
900 stamina, 950 stun.
Plays similar to 3S.
has target combo, even her jump LP->HP
far stand LP is very fast, and good poke
crouch HP is very good anti-air
Jumping step kicks = worthless?
Kunai are effective for zoning, comboable after Dragon Kick.
Ultra 2: Hashin Sho - Goes through projectiles

Juri
950 stamina, 950 stun.
Motion based character (no charge).
Very quick (Chun like) dash.
Small focus range
Hard punch kara throw?
Has a counter teleport move (qcb + p). Absorbs attack and moves behind or above opponent based on punch used.
Can combo into U2 from EX Dive Kick.
EX Dive Kick is armor breaking.
Shoots fireballs, strength of fireball determines angle: low (like tiger shot), medium, and up at an angle. Fireballs have an initial hit before being cast. Can store multiple fireballs.
Ultra 1: Feng Shui Engine - Time based, custom combo like ultra.
Ultra 2: Kaisen Dankairaku - Looks super badass.

Makoto
950 stamina, 1050 stun.
Uses a lot of meter, ex moves very good.
Crouching medium is a good poke. Combos into Hayate.
EX Hayate safe on block?
Fukiage is improved over SF3, all punches move her forward variable length.
EX Oroshi still useful.
Axe kick still useful, must be used almost immediately off the ground though.
Hard to tick into regular karakusa, range seems to have been reduced from SF3. EX Karakusa has armor.
Ultra 2: Abare - Jump cancellable

T. Hawk
1150 stamina, 1100 stun.
Good normals.
Condor Dive breaks armor.
Tomahawk Buster cannot be FADC'd.
New Move! Condor Spire - Like Hawk Dive but moves straight across screen.
Strong super and ultra.

Returning Characters
Abel
Crouching HK faster.
New Ultra! Breathless - Seems to be a great move so far, super fast start up time, grabs low and has Super Armor.
Change of Direction safer on block.
Damage seems to be increased on certain moves. Crouching Hard Punch, Cancel into Roll, Falling Sky takes off more life.
More stamina

Akuma
Far Standing Hard Kick (Double Kicks) have more start up time.
Standing Light Punch can no longer Link into far Standing Hard Kick.
Fireball, FADC, far Standing Hard Kick only works on large hitbox characters now.
New Ultra! Demon Armageddon - Up, Up + 3x Kick command. Doesn't seem to have many ways to combo into it, can't be used as anti-air. Also will miss crouching opponents. Combos from EX Air Fireball.

Balrog
Headbutt Cancel into Ultra Running Punch has revamped juggling properties. Apparently the final hit of the Ultra now whiffs.
New Ultra! Dirty Bull - 360 command grab + 3x Punch. Recovery time if this misses is fast, but seems to have a lot of start up time, for a grab. Deals a lot of stun.

Blanka
Blanka's walk speed is faster now.
Crouching Hard Punch is a better. Faster, sticks out farther and seems to be a much better poke and anti air.
Horizontal ball flies closer to the ground, apparently someone swept Blanka out of it.
Chip (block) damage on old Ultra, Lightning Cannonball, and super have been reduced.
New Ultra! Shout of Earth - This move has two versions, when done with 3x Punches it's an anti air, 3x Kicks is an anti ground move. It's performed like Guile's original Ultra move in Street Fighter 4, but you can hold the button and release it when you want the attack to come out. Seth Killian told a player the Kick version can punish fireballs at full-screen's distance, although you'll still take damage from the fireball, they'll take full damage from your Ultra. Can be thrown out of.

Cammy
Spiral Arrow better somehow.
Cannon Spike damage nerfed.
New Ultra! C.Q.C (Cammy Quick Combination) - Counter Ultra. Apparently terrible.

Chun-li
Crouching Medium Kick is much better, wasn't told how exactly.
EX-Lightning Legs can score additional hits depending on how many kick inputs were pressed.
Chun-Li's Ultra Lightning Legs seem to be tweaked. They appear to connect much more consistently from mid-screen, although some players reported problems landing them fully. Your mileage may vary. Still has juggling problems.
EX-Spinning Bird kick pushes your opponent further away after connecting and it has a smaller hit box as well.
Her Standing Hard Kick is much slower.
Crouching Light Kick 2x, Cancel into EX-Lightning Legs juggle with Ultra Lightning Legs seems to do less damage now. Less than 40% from level 1.
New Ultra! Kikosho - QCFx2 + PPP motion. Chun creates a huge fireball in front of her. Deals less damage than Hosenka. Comboable from ex legs, up kicks, target combo anywhere on screen, with EX SBK into the corner.

C. Viper
New Ultra! Burning Dance - takes off a healthy portion of life. Combos from EX Seismo.

Dan
Much better now!
Fireball now goes 60% of screen.
Can FADC DP into Ultra 2.
New Ultra! Haoh Gadoken - QCFx2 + KKK. Dan's winds up and unleashes a gigantic fireball into his opponent.

Dhalsim
New Ultra! Yoga Shangri-La - Can only be used in the air, makes it a threat when coupled with his air teleport. Small hitbox.

El Fuerte
All normals apparently faster.
New Ultra! El Fuerte Ultra Spark.

E. Honda
New Ultra! Orochi Breaker - E. Honda's second Ultra is the Orochi Breaker. Likely a 720 motion + 3x Punch command grab. He does an Oicho Throw ending with a huge butt splash, damage on this is good, but seems to be a bit easy to counter right now. Opponents cannot jump away on reaction.

Fei Long
EX-Chicken Wing (Flying Kick) may have more invincibility.
New Ultra! Gekirinken (One Inch Punch) - QCFx2 + KKK. This is a counter hit attack. Broken by armor breaking attacks.

Ken
Cannot FADC into new ultra.
Fireball somehow better.
His dashes look to be faster.
Ken's sweep (Crouching Hard Kick) might be faster.
Fierce uppercut has more invulnerability.
New Ultra! Guren Senpukyaku - A series of kicks from Ken, this can absorb one fireball and still travel through to hit your opponent.

Gen
Cannot cancel c.mk into hands.
Jumping while in Mantis (Punch) Stance goes up much higher now.
EX-Wall Dive (Oga) is no longer safe on wake up.
Wall Dive (Oga) is a lot faster now, not as good of a hit box though. For comparison's sake, it's little slower than Adon's Jaguar Tooth (Wall Dive Kick). EX Dive lost some invulnerability.
No chain combos.
Rapid Slap (Hands) seem to require less inputs to activate now. Might be 3 or 4 instead of 5 button presses.
Crane Stance (Kick) Crouching Medium Punch seems slower.
Air Kicks (Gekiro) hit your opponent up at different angles now.
New Ultras! Gen has four Ultra moves, with the two new Ultras being the Shitenketsu and Teiga.

Gouken
New Ultra! Denjin Hadoken - You can block this now. Can combo from backthrow wall bounce. Blockable when fully charged, deals 500 stun on block or hit however.

Guile
Roundhouse Flash Kick has more forward range.
Moves appear to deal more damage
New Ultra! Sonic Hurricane - Projectile ultra. Sucks. Combos from super.

M. Bison
New Ultra! Psycho Punisher - Some people compared this to Abel's Ultra in the first Street Fighter 4 game. Not a charge motion, combos from jumping medium.

Rose
Hard Punch Soul Reflect, FADC now combos into Soul Throw, Ultra 1 or EX Fireball.
New Ultra! Soul Satellite - Makes two orbs spin around her body which you can use to hit your opponent. Orbs dissipate on block as well, and deal about 20% damage each when fully charged. Can juggle into in the corner and can cross up.

Rufus
EX Jesus Kick nerfed somehow.
EX Snake Strike appears to deal less damage
New Ultra! Big Bang Typhoon! Rufus spins around in a tornado pummeling his opponent. Looks to be a real good anti-air attack.

Ryu
DP trade into ultra gone.
Fierce and strong Dragon Punch are now two hit. Only the second hit knocks down.
New Ultra! Metsu Shoryuken - Harder to combo than existing ultra, but does much more damage. Damage is reduced if first few hits miss.

Sagat
Kara Tiger Uppercut still intact.
Standing Light Kick now hits twice. Cannot cancel into moves.
Health reduced (around 1000).
Tiger Uppercut damage reduced. Can still FADC into forward roundhouse then ultra.
Has new evasion move (QCBx2 + P). It takes an EX bar to execute, but supposedly lets Sagat dodge some attacks and it powers up his Tiger Uppercut (double damage).
New Ultra! Tiger Cannon - A huge Tiger Shot.

Sakura
Her fireball does not fade out now.
Jumping Medium Kick crosses up.
New Ultra! Shinku Hadoken - This can be a horizontal fireball, or aimed upwards as anti air. Does a lot of stun. Comboable without using any meter.

Seth
Focus is worse now. Takes longer to hit level 2.
New Ultra! Tanden Typhoon. Can combo where you would combo headstomps.

Vega
Claw stays on longer now. WOO!
EX Wall Dive off the wall no longer goes through opponent.
Startup time on his Rolling Crystal Flash has been decreased.
Vega's Down-Towards + Medium Kick is an overhead attack.
New Ultra! Splendid Claw - He does a slide attack and then does a series of moves ending with a vicious looking upwards slash. You should be able to combo into this.

Zangief
Health reduced. 1100 now.
Lariat hitbox raised, easier to duck under.
New Ultra! Siberian Blizzard - 720 motion + 3x Kicks in the air. This grabs an airborne enemy, but also, reportedly, a grounded opponent if you're close enough. Comboable from FADC Lariat.