I'm not sure if I was watching the same movie as the other reviewers that have all left 8 and above, it begs the question of what they rating they give a good film.
Personally I'm a big fan of British movies, I do what I can to see them and rent them when they come up. I have a lot of faith in the acting and writing of fellow Brits to deliver. From Blackadder to Four Lions there's a lot of genius in British comedy. Sadly none of it is here.
That said the dialogue and direction are good, there was plenty of quality that helped mask an underlying problem. Eventually the dialogue seems to become very repetitive. After an hour I'd got bored of the whining of the protagonist and the sheer banality of his mate, with too few laughs to lift the movie from being dreary. Just because a movie has men wee-ing in it and talks about STI's doesn't make it edgy or even particularly clever and it certainly doesn't make it funny.
5 stars isn't bad for me and its a nod to the positive aspects of the film. It's better than I could do, but it isn't good.