Oh, geez. As much as I'm in love with Joseph Gordon-Levitt and his acting skills, I hated this movie.
The thing that annoyed me most was probably the sex. It was as if the movie was saying, "No matter what the situation is, whether you're on the roof of a building or otherwise, you can always get naked!"
Apart from that, the movie was just plain boring. It might be my taste in genres, but the "drama" part of the film almost put me to sleep, and the "thriller" part was too interrupted to really be appreciated.
Acting-wise, though, Joseph Gordon-Levitt rocked, and from what I remember, Lynn Collins wasn't too bad, either.