They could've done something great with the psychological aspect (a girl having to turn herself to a sex object in order to escape), or they could've at least produce some quality gorno. Instead they delivered neither.
A barrel-scraping exercise in freak family horror that's about as redundant as films within the genre come, the hopelessly inept and thoroughly derivative Summer's Moon is one of a million pretenders to The Texas Chainsaw Massacre to miss that film's point of brilliance and lamely re-enact its themes for horror "fans" with little appreciation of film history and resistance to across-the-board incompetence. It has its fleeting sick pleasures but is an indisputably worthless movie.
I liked Summer's Blood. It isn't an amazing film, but it's a good thriller that has some interesting characters, a somewhat unique plot and enough substance to keep you engaged throughout. The beginning isn't all that great though, and I hope that doesn't dissuade anyone from sticking with it, as the main portion of the film is worth watching. Its ending doesn't provide the sense of closure you would hope for, but at least it makes sense, unlike some other thriller endings.