6.5, so above average. I'd recommend never reading the reviews for this movie before you watch it. I barely read the description, because I was told "the less you know, the better", and it's extremely important for this movie. I think it'll even be boring upon a second watch, now that I don't have to think and guess as I had upon the first.
So, major spoilers. You have been warned.
I have many complaints and many great things to say about this movie, but like the miserable couple in it, I will focus on the bad parts. So, what I gather from the premise is, there are always one couple in the house/quest house that can't leave, because their relationship is not strong enough. And, when some new couple come visit,(guided by some psychopath Doctor Who-ish therapist) the trapped couple tries to switch places with them. They do so, by taking on an idealized form of the new couple, the female seducing the male and so on... And then, when the new couple's relationship is weakened because the trapped couple's fake personalities appears to be so much more awesome than their partner's, the trapped couple can leave, making the "new" couple become the trapped ones instead.
This left so many questions, that will frustratingly never be answered.
1) How do the trapped couple shape shift into the idealized forms of the other couple? Is it magic? Quantum mechanics? I don't know, and neither does the movie.
2) So at the end, the male lead realizes that he has escaped with the idealized version of Moss by mistake. He decides to just roll with it, since his original wife coldly and knowingly decided to stay with his fake version - I totally get that. What I don't get is the fake Moss-character's decision to stay with him after she escaped. What's in it for her? She must've gone insane trying to keep up the idealized act forever, given that she is also a real person, who had another life before.
3) Related to the one above, are the shape shifting permanent? Do they have permanent fake personalities as well, never being able to reclaim the life they had before? Are they forced to do this, simply because they wanted a better relationship?!
4) What point is the therapist trying to make? After all, all of the couples entering the house/guest house, will have their relationship destroyed, and then be forced to shape shift into a stranger's idea of perfection. They don't get anything fixed, only cruel punishment awaits.
Some people say this movie would've been better as a short. I say this movie would've been better as a horror. It was, in fact, recommended to me, because I was searching for a scary movie(damn you, Metafilter, and your ever so tame idea of "scary stuff"). I'll never forget the creeped out feeling I got when I saw Kate Moss holding a babushka, realizing that this would be about doppelgängers, but sadly not knowing that it was intended to be a drama-mystery- comedy.
Thus, I sat there waiting in glee for some revelation of the terrible creatures behind the perfect facades, or some build-up to an incredibly freaky psychological horror. They could've done so much with this! I wish they were aliens or something, with a slow, scary revelation of creepy habits, that would make the couple regret their decisions. Or maybe they could've just played around with the surreal feeling of being with your partner, but not really, and the surreal states and psychology that follows living with a fantastic being, that knows it's not real. Yet the simple concept of the movie stayed as minimalist as it was when it begun. Shame.
And one last thing. The Kate Moss-character was surprisingly, well, stupid - the fact that she turned out to be "right" in the end didn't prevent me from strongly disliking her, in all her "but if it feeeeels right"- pretensions. I actually thought what she did was worse than the male character cheating, but most of all, I just couldn't connect with her. She lacked both curiosity and fear in a way I found unbelievable, and I actually understood her shape shifter-version much better.