I'm really surprised there's not a thread on this yet. Search is broken for me as usual but I ctrl + Fed through a few pages of the movies forum.
Anyway, wow. What a spectacle this movie is. I would watch it again in the theater even just for the visuals/landscapes, it's quite remarkable.
The acting was very good all-around, though I thought Fitzgerald, Tom Hardy's character, was written a bit too one dimensionally. That's really the only criticism I can think for it at the moment. It's certainly not for everyone, it's basically a relentless 2.5 hours of intense frontier survival.
It didn't occur to me as I was watching but now that I think about it, it reminds me of Blackhawk Down a bit. A group is out in a dangerous area, shit breaks bad, and the next two hours is the intense, often hectic aftermath.
Even if you aren't interested in the frontier revenge plot, if the visuals/cinematography of movies interests you I can't recommend this enough, it is all at once foreboding, harsh, and beautiful.