It's not terrible. The two societies are different in interesting ways, and Rist makes a good naive traveler. But it is, once again, not a story but an excerpt; we've already missed the beginning and there is no real ending.
There are other problems as well. For one thing, Rist seems remarkably dim. It takes him an unbelievably long time to realize that the sun covered by mists in the Tharn's Lands is the same as the shining sun in the Warm Lands. He learns Warm Lands' words for things -- "day" instead of "dim," for example -- and yet every time he goes to use a word he forgets it and has to remind himself, or someone reminds him. (The Warm Lands' words are all italicized -- west and east and morning and Shining One -- something that started to drive me up the wall.) And it's not just Rist who seems none-too-bright but everyone from the crew. At one point Rist waits patiently until Cruthar counts up to three.*
I don't know if this is intentional -- if the Tharn's Landers are actually not as smart as the Warm Landers, maybe even another species. (They look fairly different.) But it's something the reader should be able to figure out.
The writing is pretty hard to get through as well. There are far more adjectives than necessary: "'Welcome to the Warm Lands, bird-rider!' his rough berg-companion Cruthar shouted back, also trying to be heard through the thunderous crashing, sharp creaks, and long groans as their shepherded small mountain of ice slid and pounded against the river stones." There's a sharp point-of-view switch, when with no warning we're in Cruthar's head instead of Rist's. At one point we hear about Rist's father's "advanced literacy in reading" -- as opposed to, I guess, his advanced literacy in basket-weaving.
Like I said, though, it's not terrible. There's some action, finally, after pages and pages of exposition -- although, unfortunately, the most interesting part seems just about to occur when the story ends. But there's nothing new here, nothing that stands out or makes this worthy of a Hugo.
* Fairness compels me to admit that something else may be happening here. Cruthar is making several points to Rist, and has gotten through numbers one and two. Then he pauses, and "Rist waited while Cruthar struggled to count up to the next point." So Cruthar could be trying to think of the third point, but that's not how I read it at first.