Serious young adult lesbian drama or hot girl-on-girl action?
I can't entirely decide. But maybe they're not mutually exclusive.
I've heard some actual lesbians don't like this movie because they cast two very heterosexually desirable actresses in the leading roles (they're also not very believable as teenagers, but that's understandable). But I think that this criticism is selling the movie short. The lesbian sex scenes are memorable, but so is the rest of the movie.
Movies do tend to make lesbian sex more acceptable and palatable to the mainstream audience, but they do the same thing with straight sex scenes. God knows, I don't want to see the average straight couple having realistic warts-and-all sex either, but that won't happen in a movie. Beyond the sex scenes though, I think this a very well-made movie.