I watched this film with a sort of dangerous fascination, like a hedgehog trapped in the headlights. There is no doubt that (even if you enjoyed it) it's a bad movie, but the important question is why? It has a good cast; it's lively; it's prepared to tackle sex head on, with some of the characters actually getting some of it here and there, which is unusual for a British comedy. It also has Johnny Vegas and Mackenzie Crook, Marmite performers agreed but they've have had their moments in the past.
What it's principally lacking is charm. The characters are impossibly idiotic, unbelievable and alienating, so that instead of a film of Men Behaving Badly the producers have made Game On. Any mediocre writer wanting to make a film about the sexual attitudes of dozy, sexist British men would have got hold of a few copies of Loaded, Zoo or even Viz to read Sid the Sexist and the thing would have written itself. Instead, the producers clearly tried to make up some moronic, difficult to care about, characters. Character comedy - as opposed to slapstick etc - only works if the audience can recognise some human truth to the situation. But watching this film is like being told an annoying joke that you know is not going to end up funny but you can't stop it.
Sadly, the film is also poorly made. The plot structure is weak, there's little character delineation or development, and many of the scenes aren't funny. Time after time the same lame reggae chips in to divide scenes, pointlessly and gratingly. There's a lot of needless repetition - when you've done one joke about parking outside a sex party you don't need to do it again. One wonders what the UK Film Council saw in the script.
This is a world where most men are rakes, and most women are continually up for it. The Apartment and Alfie satirised much the same world view, but the producers of this film accept it without criticism. Thus they've ended up with a kind of inferior update of Confessions of a Window Cleaner. Somebody British needs to have another go at this kind of thing, and do it properly a good next project for Simon Pegg and Edgar Wright I think...