And with this and "History of Violence" David Cronenberg and Viggo Mortensen might be the most intriguing director/actor pair out there. Suck it Soderbergh/Clooney!
Also, add Cronenberg to the list of directors who are doing some of their most interesting work late in their career. Cronenberg's always written his stories on the flesh of his characters, it's just taken him about 40 years to do it with any hint of subtlety (not that I don't love his early non-subtle work, I just think it kinda petered out with "eXistenZ"). Here, the story is literally written on the character's flesh, as tattoos tell the life stories of Russian gangsters in London.
I could go into detail and praise the acting of not just Mortensen but Naomi Watts and especially the villainous Vincent Cassel, but I'd rather just say that the 89% tomatometer rating is completely deserved, and leave you with two thoughts. First, the fleshy (a)moral obsessions of Cronenberg are so pervasive and yet so understated that just attaching Cronenberg's name to this movie automatically changes my reading--if this were exactly the same frame by frame but not a Cronenberg movie, I'd read it very differently. Second, the audience at the Toronto Film Festival who voted this their favorite movie have quite a taste for blood.