Final Fantasy 13. It is the best of games and the worst of games. Here is my experience with it.
Final Fantasy used to be my favorite series of games. I would always buy the games day 1 and then just do nothing else in my life but work and then come home to play the games until I'd thoroughly beaten them including all endgame content. So I bought Final Fantasy 13 and came home excitedly to play it. The game looked stunningly gorgeous. But I felt it kind of sucked (at first). I only liked some of the characters, but the worst part is just walking down a hallway and fighting stuff that has no challenge. There are no towns, and really nothing to interact with. The story is only so-so and harder to follow the deeper in you get. I kept playing out of spite. I spent my $60 and I was going to get my money's worth damn it! So I kept playing, and my wife and I would just make fun of it.
Then around 20-25 hours in, the game actually started getting good. And when I got to Gran Pulse the game became amazing! It turns out in the end I played 100+ hours of the game. I think I played all of the optional content. The game seriously left me wanting more.
If I could somehow remove the first 20 hours of FF13, then it would probably be my favorite game on the PS3. The last 80 hours of the game are that good. But I've only played through the game once. The first 20ish hours are just too painful. I might actually play it again at some point, but I'm not really looking forward to it.
The sequels: FF13-2 and Lighting Returns are also seriously fun but seriously flawed games, but for different reasons. I remember enjoying them both a lot, but at the same time Final Fantasy is not my favorite series anymore and it mostly has to do with the FF13 series. I just don't trust Square-Enix to do a good enough job anymore. They still make good games, but Final Fantasy is just not on the same amazing level that it used to be.