Joseph Gordon-Levitt plays Tom Hansen, a twenty-something who gave up on his dream of being an architect, and now works at a greeting card company, writing copy. One day, a new girl, Summer Finn (played by Zooey Deschanel), starts working at the company as the assistant to Tom's boss. They eventually, after a lot of high school antics, end up together, have a relationship, and then break up.
Webb wraps his tale in a very seering reality, and it feels like the things these characters are going through are things that all of us of that age have gone through, said the same things, felt the same things. Somehow Webb, and writers Scott Neustadter and Michael H. Weber, connected into the zeitgeist of love at this very moment and managed to make it into something totally unromanticized or un-Hollywoodized. Much like Juno or Nick and Norah's Infinite Playlist, or even Lost In Translation, to some extent, (500) Days uses the perfect mix of clever writing, subtle and endearing art direction, and a mixture of pop and indie rock to tell our generations love story.
One thing I would like to point out, as well, is the writers GENIUS addition of the concept of Tom basing his belief in destiny by misreading The Graduate. It's not difficult to see the hard reality of love in that last scene of the movie, when Ben and Elaine have escaped the wedding, and their happiness dissipates as they get farther and farther away. Summer gets this, and see's it happening right in front of her, but Tom still believes, blindly, that his love will be enough for both of them. It's a hard reality that most people discover in the most awful times of their lives - sometimes love and good intentions just aren't enough to hold a relationship together.