We're warned at the beginning that (500) Days of Summer isn't a love story, but it is. It just doesn't play by the rules of a standard love story. In fact, it doesn't play by any rules except its own, and that's what makes it so much fun.
It's the story of a relationship between a girl named Summer (Zooey Deschanel) and Tom (Joseph Gordon-Levitt). The relationship lasts 500 days, but the story's not told in chronological order. It skips around, but the numbers are flashed on the screen in parentheses (as in the title) so you know where you are. I'd describe what goes on and how different it all is, but it's really the kind of thing you should find out for yourself. (I seem to say that a lot in my reviews, but it's always true. Trust me.) It provides everything from quiet smiles to belly laughs, and there are a couple of exhilarating scenes that took my completely by surprise.
The performances are perfect. Deschanel is just mysterious enough as a young woman who always keeps a little bit of herself hidden, and Gordon-Levitt is just as good at playing a young man whose feelings are often all too obvious. His sidekicks are great, too. And Chole Moretz steals all her scenes, in preparation, no doubt for her upcoming role in Kick Ass, which is a slightly different kind of movie.
You probably have to be in the right mood to enjoy a movie like (500) Days of Summer. If you're looking for Rambo 6, you're in the wrong place. Even if you're looking for, say, You've Got Mail, you're in the wrong place. Think more along the lines of Annie Hall. And then check it out.