As splatbooks go, this is a good one. Not perfect, mind, but the parts about climatic and other environmental hazards are spot on. While I had looked forward to the cultural sections, I was a bit disappointed in how they were implemented. If, for instance, one is going to do a section on Ice Age Neolithic culture, just go ahead and mention that an Atlantean culture might be going at the same time, and put out a separate book for that, where you have the space to do it right. Still, Norse, Eskimo/Aluet/Tlingit we all fairly good (don't see myself using the classes given, mind, but fairly good), and adding a Slavic section, with a very Fairy Tale flavor, was unexpected and welcome.
I would say that one might need Frostburn as well as this one to really nail down a sub-artic (or arctic) campaign.