There are a couple of laugh out loud moments, and the horror is of the very visceral kind -people not obsessed with gross special effects will find themselves wanting to look away as the next horribly gory interlude looms. At least the plot requires you pay attention, and there's a decent enough narrative running through the film.
The story revolves around two brothers (Reece Shearsmith, Andy Serkis), who have kidnapped the daughter of a mob boss, hide out in a cottage, and watch their night going from crappy to just-about-as-bad-as-possible.
Andy Serkis (Kong, Gollum) is very good and has the advantage of being given the only half-way likable character to play, as feckless, boat-loving, lead kidnapper David.
All of the actors are competent; the problem is with the characterisation - although everyone plays their roles naturalistically (thank you!), what they have to work with is a role call of hideous stereotypes. Unfortunately this doesn't work as the hilarious parody it was no doubt intended to: it just clutters the film with a too large assortment of irritatingly 2D people, including 'psychotic Chinese gangsters' 'London mob boss', 'hen-pecked looser' etc.
Worst of all is the unfortunate casting of Jennifer Ellison, who has apparently been brought up apart from the rest of her family in a Liverpudlian tanning salon run by vipers. It must always be a temptation for any writer/director to produce a film that has more swear words per square centimeter than any other in the history of cinema, and usually I'm keen on a good salty dose of Anglo-Saxon. Half way through this though I started dying a little inside each time Ellison spat out the F word.
End of film heads-up: There's an additional chunk after the credits for those who don't like missing that kind of thing.