disappointing considering williams previous work (spoilers)

I was really looking foward to this after having studied London to Brighton in my film studies class and really liking the film, especially the direction and story. The film started of with some beautiful shots and to the films credit is its one strong point the cinematography is really good, but the film was too slow, I don't mind slow films if they are interesting but this wasn't particularly. The acting was ok the parents in the house were good but the chavs weren't particularly well the main one was a little bit weak, the story was ok but there were tons of things happening that I questioned like why would you bring your little *beep* brother along with you, and the ending was very lack luster (SPOILERS), none of the bad guys got killed apart from the main one I guess, but I'm not sure as you couldn't see if he was actually dead or not and I guess you were supposed to be sympatheic to the other black one (I can't remember his name) but I just found him annoying and didn't understand why he was there and why you're supposed to like him coz he brought someone a glass of orange juice, also the whole leaving it on a "cliffhanger" was stupid coz why would he really kill the kid, he let everyone else run past him without making a huge effort to catch them so why kill the little kid. The annoying thing with this film was that it was just so average, it wasn't bad or good and coming from such a promising writer/director that is a real shame. And you'd expect that if the film is average you'd at least get some good gore but nope, nearly everything is off screen including punches and kicks and can someone please tell me how this is an 18 that is so ridiculous I've seen so many more violent/threatening/disturbing 15s than this having to be 18 to watch this, someones having a *beep* laugh