I didn't know much about this film - both its attendant controversy and its gruelling nature had passed me by - but what I did know was enough to make me strongly suspect that it was going to be a downer (I'd intended to avoid the film, but Jade wanted to see it). In fact, it was one of the most uncomfortable films I've watched in a while - entirely deliberately so - Ryan Gosling and Michelle Williams disappearing into their characters and delivering a naturalistic, almost improvised-feeling rendition of the lives of two people, unhappily married, alternating with scenes from seven (?) years previously, when they first met. (Gosling in particular is fantastic - he's an unassuming-seeming actor, but seriously talented...he was equally good in a very different role in Lars and the Real Girl.)
The discomfort came from the way that the characters are unpleasant to each other, Gosling's Dean in particular. There's physical and emotional (including sexual, which is both) violence and bullying, but more than that, there's two people just unable to get along, trapped by circumstance and by who they are; the oral sex scene which has caused so much fuss, while moderately explicit, isn't troubling at all, and that's because of its context - it occurs early in the relationship, while they're happy, before everything goes gradually to hell.
I was glad that the film didn't overly play up the contrast between the 'early' scenes and the later ones - there are plenty of signs of what's to come in those early sequences, though much more light and promise too. It makes it more realistic, though of course it's that realism which causes much of the squirming.
So definitely a downer (though the actors' comments at the very end of this interview gave me a slightly different perspective on it), but impressive.