It is a good game, thought it is lacking endgame content, but I cannot fault it for that because it is a new game, and it had the smoothest launch of any MMO I have seen. I would recommend you try it out once it has a free trial period. You pay $50 to get the game and a one month of game time. For MMO's this is one of the once at the top, it is not perfect by any means, but it is fun to play.
What makes it special is that there is allot of verity when it comes to the kind of character you can build. This is achieve on the Class tree system, you have four classes to choose from. They are Warrior, Rouge, Mage, and Cleric. Each class has 8 sub classes known as souls, for each character you can only choose three of each soul. I have an example of a Rouge tank build that I am currently using,
here.
The last thing about Rift, is what it gets it's namesake from, the Rifts. These are open world instances that drop mobs into the world, not closing the Rift can cause an area to become unusable, ergo: NPC's that give out and receive quest, the guard NPC's are not much more powerful then your character, they can be over run by mobs spawned by Rifts. which you 'have' to group up with public groups to take out the offending Rifts, which the game pretty much does all the work for you. It pops up a little message to every one in the area, and before you know it, you have a raid sized group of 20-30 players, at lvl 15.
Pretty much, if I had the money, and the time I would continue playing this game. it is worth it, IMO.
Wiki
Wiki overview of Classes
Class builder