this book has real possiblities if you are interested in doing a artic or a cold environment like in the George RR Martin series (game of thrones)
You are introduced in the opening chapter of the frostfell environments of high altitude, winter, ice age and lands of eternal ice. The dangers are listed like freezing, snow blindess, dangerous terrain, etc. There are listed specific terrain types, like tundra, frozen seas and the like.
Chapter two has the various races of the frostfell, mostly adaptations of the current ph races plus the uldra, a small fey who live in the cold. There is a section on the various classes and how they fit into this environment. There are new feats, but not alot. One of the feats is snowrunner which allows you to run at full speed, another is piercing cold which allows you to add the cold descriptor to your spells.
There are some new prestige classes which look hit or miss to me. It would depend on the DM to pick and choose. One of the prestige classes is the frostmage who gains natural armor, resistance to cold in the first two levels of the class.
There are new equipment and spells. There are several conjure ice beasts(summon monster equivilent). Ice shield gives damage reduction of 15, freezing glance which freezes subject in their tracks.
New monsters like the dire polar bear,and the wolly mammoth. The book ends with some adventures, always a good idea in my opinion.
If you are creative enough, you can do without this book.
I am planning on a series of adventures for my players and I find this to be a useful book, especially for the hazards of the cold and some of the monsters and spells