This review may contain spoilers. I can handle the truth.
It's like "Before Sunrise" - with tentacles!
"Shame" accomplishes what (fortunately, I guess) few movies can: it is highly compelling but also equally repellent at the same time. While on one hand it's an outstanding piece of cinematic craftsmanship (McQueen and Fassbender working together seems like a perfect match) and a definite "must see", on the other, I probably never want to see it again because it's pretty much not an enjoyable experience, at least in the conventional sense.