There are a coupla different styles in this movie, which I guess some viewers may find disjointed ... but it worked for me.
The first 20 minutes are just plain funny, highlighted by Katy Davis as Jean, the most amazingly self-obsessed, annoying and hilarious character I've seen in a while. But, after Jean has a little accident, the movie becomes more serious ... though with some moments and dialogue that reminded me a bit of Guy Ritchie.
The last half of the flick is pure thriller, very well done and not at all predictable. You will NOT be bored.
You also get to see the wonderful Kelly Reilly (Viv) in a fairly early role ... she's beautiful, and she definitely can act. Sadly, I suspect her days of low-budget thrillers now is past, so you'll have to settle for this one. For later roles, check her out in "Eden Lake" and "Sherlock Holmes."
Enjoy!