Hundreds of areas to explore, and even more still quests to accomplish. True multi-classing where you play using spells and skills that you select from a range of disciplines, as your own unique blend of mage, cleric, thief, warrior, necromancer and druid. Learning the game is easy, as an immersive storyline leads you through initial quests to teach you the ropes, while still giving you freedom to explore unrestricted... save for whatever foes may cross your path.
The player base is active and extremely friendly, as are the administrators. It's difficult to connect to the game and not find dozens of people engaged in exploration, battles, crafting or just congregating in an area and talking. For those looking to connect with others, you won't find a better group of people to help you along in your quests.
The interface is highly configurable. Those escapist players looking simply to immerse themselves in another realm can disconnect from public channels and explore mostly by themselves. The help system and in-game libraries are exhaustively extensive, but offer reliable and convenient search mechanisms to help you find exactly what you need. And the interface can be extended easily with in-game aliases that can be defined to simplify complex commands, or to provide quick shortcuts for frequently used sequences of commands.
All that's available without even considering the companion application that's available for download, which extends the game further with other features and sound packs. And it's an understatement to say the game is extremely friendly to visually impaired players, which includes the majority of the player base.
The cost is also right. It's free. If you really enjoy the game, and find yourself dragging around more than a hundred or so items, you may be tempted to lighten your load by buying a weightless container or renting a storage locker, but those are entirely optional and not at all necessary for gameplay or advancing in levels.
A game so fun, one might even compare it to.... Heaven.