The main problem with this film, and indeed with many films set in the outdoors, is that it's too long. Maybe it's because I'm a product of the city and the suburbs, but to me, most movies set in the outdoors that don't use the scenery to advance the plot or set the mood, but rather just want to gaze at it, bore me quickly. It's like, "Yes, it's beautiful, let's move on." Also, though I like Brad Pitt, he doesn't always do the job with his Austrian accent; even when he gets it down, you're always thinking, "That's Brad Pitt doing an Austrian accent," rather than, "That's Heinrich Harrer." And that whole subplot about Harrer missing the son he's never seen doesn't work.
Still, there is much to like in this film. In many of these "white men in strange country" movies, the emphasis is on what the white man teaches the people in the other country, and that's somewhat condescending; here, it's on what the people in the other country teach Harrer, yet his story isn't made more important than the story of the Tibet people. Also, though his accent doesn't convince, Pitt is convincing as Harrer in the physical sense; he looks like a former skier and like the blond, blue-eyed ideal of the Nazis. And finally, he's convincing in taking us through Harrer's transformation.
Two more things; one, someone in their comments wondered how the Dalai Lama knew so much about Western culture. According to the book, Harrer found the Dalai Lama to be quite curious about the world around him, so he studied what he could. Also, the film meets head-on the controversy about Harrer being a former Nazi; it doesn't soft-pedal his past at all, which makes his transformation that much more convincing.