Okay, in brief: I'm pretty satisfied with the book, though glad I got it at discount.
There's a lot of good stuff in this book. That said, it's really a collection of mini-campaign settings with extra monsters and rules to support that, rather than the other way around.
For instance, many of the spells and feats take their name of origin, rather than a generic-sounding one. I can see spells like
sbatatdaq being renamed real quick.
Another aspect is that MGE seems to have put more emphasis on the actual legends and practices of the given cultures, rather than making the items balanced for a generic fantasy game. It ranges from the silly (singing construct pastries) to questionably balanced (the Voelva PrC is cool, but impossible to use in combat situations), to the absolutely great (Kam are monsters that cannot be damaged normally; instead, when hit, they split into two Kam, each with half the original's HP!).
I do love the detail on the various cultures, and how well-tied the material is to them. If you want to run a Norse campaign, or a Slavic campaign, it's nearly perfect.
However, divesting some of the rules from those campaigns does not look to be easy. It would be simpler to find a niche in your campaign for inserting aspects of the culture, and allowing players to take bits 'n pieces from there to use.
That said, there's plenty to love here. The first chapter is an in-depth examination of arctic and sub-arctic climes, which goes into great detail on terrain, the effects of weather, and hazards. I pity the adventurers who get caught in a
jökulhlaup!
A chapter on racial variants follows. For the most part, it seems very well done, and offers several subtypes of the standard humanoid races to choose from, as well as which cultural setting they're suited for. I love the author's take on halflings, for instance, especially the "Little Fist" subrace for Slavic campaigns. The addition of Neanderthals as a half-orc 'subrace' is a nice touch for any setting that lacks orcs.
The equipment chapter is equally meaty, with lots of new weapons and armor suitable for most campaigns. Given that many arctic cultures rely on the sea, there are several boats and ships statted out, which should prove quite useful.
Feats are perhaps the most contentious part of the book, in my opinion. Feats like
Behead make sense, and provide a good way to quantify a house rule that many folks already use (insta-kill). Others, like
Evil Eye fall prey to the concept that appearance = Charisma, and losing your looks means losing points from your CHA stat. In fact, many of the feats given directly affect your stat values.
While some look balanced, other feats would be a bit overpowering for a traditional fantasy game (such as
Returning Ammo), or have some strange roleplaying restrictions (
Orphan). Overall, it's a mixed bag. DMs should pick and choose carefully to suit their campaign.
The same goes for the magic chapter. While most of the spells are quite useful and flavorful, a few are either overpowered or just a bit confusing. As an example, the
maturity rite spell is apparently a requirement for level advancement in an Ice Age campaign, but can only be cast by a 5th level Adept or Druid. This fact is never mentioned in the Ice Age campaign chapter, meaning it could easily be overlooked, and could be more easily handled through roleplaying than as a spell.
I have fewer problems with the monster section. There are some wonderful creatures, such as the Corpse Shroud, Cold Stranger template and aforementioned Kam. A few weird ones crop up, such as the Snowman Golem (literally described as "two large balls of snow, with a carrot for a nose, buttons for eyes, branches for arms and a hat of some sort.") No one can accuse the MGE folks of lacking a sense of humor.
A short section of magic items follows the monsters, including new weapon and armor effects. Again, the Cha = appearance idea crops up, but overall I can't fault the authors in this chapter. Many of the items here are classics, especially the Apple Of Sleep.
Finally, we get to the culture chapters. Here you find a brief discussion of the various cultures, how they fit into a campaign world, and various classes & prestige classes to add suitable flavor to your game world. Most of the PrCs are tied heavily to their particular culture, as should be, though this makes it more difficult to just drop any of them into a standard D&D game. Favorites of mine are the Koldun and Glimumann, while others (the previously mentioned Voelva) have some problems being useful for PCs. Some of these classes would be best restricted to NPCs.
The overall look of the book is very good. Though the font is larger than your PHB, and there's a bit more white space, the text is very easy on the eyes. Artwork ranges from average to absolutely excellent, with Andy Braz's monsters falling into the latter category. A very nicely done work of short fiction introduces most of the chapters, telling the continuing story of a native arctic group struggling to survive the intrusion of strangers, and ties rather well into the feel of the book. Culture is emphasised throughout the book, though they understandably can't go in-depth in a gaming supplement.
Overall, I'd recommend the book if you're interested in an arctic or sub-arctic campaign setting. It would certainly make a good addition for DMs wanting to run a game in The North region of the Forgotten Realms, for instance. However, it may be more time-consuming to convert and balance than casual DMs and players would enjoy. Also, until MGE publishes errata to correct the OGL in the back of the book, the spells chapter isn't open for use by other publishers.
If you're willing to put in the time to use it, and have the spare cash, it's worth it.