Short version, I liked it, a well made summer movie with excellent casting.
What makes this better than a lot of summer movies is tone; it's sincere but prepared to make jokes about itself. That levity can be hard to get right, but this does (bathroom scene got a lot of laughs).
I think it drags a bit in places though. I was looking at my watch occasionally.
But I've realised I've lost interest in high school as a setting. I don't think the film handled it that badly, but I just don't relate to it anymore. It may pass but it's my problem so nothing the film can be blamed for.
A late edit, but I just remembered something; when Logan Marshall-Green was in 'Prometheus' everyone said he looked like Tom Hardy. Now in this film, it was a few minutes before I realised that he wasn't Jon Bernthal.
He's clearly a good actor and he's getting roles, but he seems to be a sort of master of disguise, as other actors, in those roles!