If you've already seen the endings, then that removes a fair amount of the fun and mystery.

X-2's depth and intrigue is quite well hidden, so it's harder for some people to get into. Also, some gamers expect every FF to be a carbon-copy of the last one, so they're naturally going to be in for a disappointment.

If you just try to bear in mind that X-2 is a different kind of game with its own style and pace, then maybe you'll find something to enjoy in it. Like the five or so different sub-plots that build up during the game, shaped by the player's own choices and actions. People usually whine that this kind of thing is missing from the recent FFs.