The early game can seem more difficult due to the fact that combat is incentivized from level 1, but eases up in difficulty due to a variety of new methods you have of adding offensive and defense to your character. The progression from 0 to hero in 3BFTweaks is very smooth; there's always a pressure of difficulty but always ways to accomplish your goals.
Many things have been rebalanced to attempt at making everything worthwhile and not pressuring people into using the "meta". Optimally making your character will always be incentivized, but the "optimal" route to power isn't so absurdly more powerful than its weaker competitors that you can't adventure on a weaker character.
This eliminates skill grinding and takes a lot of the need for "optimal" play out of the game-- no longer do you need to worry about how many times you cast Summon Skeleton in battle; just kill the stuff and you'll level up all the same.
Systems have been added to promote spending less time micromanaging divine blessings, buff effects, selling things, or grinding crafting skills. If you want to do 100+ hour characters who tour the world and do everything there is to do, you will probably run out of ways to make your character stronger.
Leveling rates are completely configurable in the MCM for those who prefer to have longer (or shorter!) games.