I had no idea what to expect, but I liked it a lot. I think a mature teenager (especially one in public school) would be able to handle everything the movie threw at them. No graphic sex, minimal if any blood, and language that is probably no worse than what the kids see written on the bathroom stalls.
The main character lies to her parents, but faces the consequences. Her friend drinks (Bliss doesn't) and gets arrested for it. Bliss gives her virginity to a guy she thinks she knows and loves, and he cheats on her and doesn't call her afterwards. All very realistic things teens do, and all very realistic consequences. We were a little embarrassed by some of the sexual content, but there was nothing graphic, and it was mostly because it was unexpected.
It wasn't a stereotypical sports film, and I absolutely loved that. There were several pleasant surprises that kept me pulled into the movie. It felt... realistic in a good way, much like Juno. I think a world-savvy teen will be fine watching it, and my aunt swears it was perfectly appropriate to her two young girls, who probably were too young to get most of the jokes and drug scenes.