TV spots have started appearing for this here in the UK, as it's released to cinemas tomorrow. I found this trailer; don't know if it's the same as the one posted previously:
Looks like it's trying hard to be "The Inbetweeners", but with werewolves. I'd say we've got about a 50% chance of the plot being exactly as advertised (she's the werewolf) or there being an "unexpected twist" (she's not). I'll pass on the cinema trip and catch it on DVD...