Final Fantasy X was probably the first real, big budget RPG I ever played, and I basically love it to pieces. I also enjoyed playing X-2, though. Whether you'll like it too will depend on a few things (in my opinion).

1) Can you tolerate some girly / stupid stuff? FFX-2 is divided into several chapters. I think there are five, if I remember right. The first two chapters are basically the three female main characters running around doing random stuff while being annoying and bubbly. After that, though, they discover evidence of _____, and uncover a plot to _____, etc, and (believe it or not) the story actually becomes very somber, and even somewhat dark. Unfortunately, most people don't make it beyond the first chapter or two before putting the game down in disgust. I'm not necessarily saying they shouldn't, either; 2/5 of a game is a lot to work through before you get to the good stuff. So. Yeah. If you can't tolerate some bubbly annoying absurdity for a while, you probably shouldn't play the game.

2) Did you enjoy FFX's world, atmosphere, related characters, etc? One of the things I enjoyed most about X-2 was going back to my old stomping grounds, and seeing how the world had changed since the events of X. Places change, characters change, relationships evolve, etc. If you couldn't care less about that kind of thing, and don't care a whit about the FFX world, that's a strong mark against playing X-2.

3) Do you care what happened to Tidus? Without spoiling anything, a large part of X-2's plot revolves around Yuna reminiscing/wondering about, and searching for, Tidus. If that sounds retarded and you wish they'd just leave the Tidus thing alone, X-2 is probably not for you.

Anyway, those are my terms. If you enjoyed the world of X, and the end of the game left you wondering what happened to Tidus, you'll probably enjoy X-2 (assuming you can tolerate some stupid stuff at the beginning.) X-2 has some solid game mechanics (job-system battles are fun), an average main plot (save the world from just-now-discovered Bad Thing), a good dose of humor (the airship pilot is actually hilarious, in a weird way) and the high level of polish / atmosphere you'd expect of a FF game.

Basically, what it boils down to is that X-2 is a very well made fan-service game. If you're a fan, you'll like it. If you're not, I imagine you'd still enjoy it, I just couldn't necessarily recommend that you play it instead of something else. It honestly is a good game, though, and most of the people saying it sucks are just hating on the bubbly girly stuff. Yes, that gets in the way, but there's a good game underneath it all, and I think it's too bad that more people didn't give it a chance.