This unusual movie was very well done, but overlong. The story arc is predictable, but the journey is worth the ride.
The odd camera angles do indeed help us feel Mark's discomfort. Even in casual conversations we alternate between overly tight head shots and very long shots; the camera never allows us to become comfortable with the situation.
I disagree with Missipecac in one area only. This film does indeed directly laugh at, and allow us to laugh at, the traits of OCD. I noticed, however, that this only happened between OCD sufferers. The outsiders in the film never laughed. They were always uncomfortable, frightened, distant, or confused. And the viewer was never given the opportunity to laugh in these situations.
It was only when the OCD sufferers could let their guard down and laugh (instead of crying) that the viewer could laugh along with them.
The predictableness of the plot did make for a movie that was too long. It could have been a good 10-15 minutes shorter. Even so, there was one obvious reference to a scene that was cut that I found quite jarring.
I was a spouse of a person with a major mental illness (not OCD). I would have liked to see the wife drawn a bit more fully. There were hints at her underlying sadness, regret, and guilt, but only the tiniest of hints.
I think this movie is a MUCH better examination of OCD than As Good As It Gets with Jack Nicholson. That movie was insufferably cute. In Dirty Filthy Love, even when you laugh at OCD, you never, ever find it cute or quirky.