While neither Lovecraft, nor anyone in his circle that I'm aware of, ever wrote about anything quite like ratmen, I couldn't help but be struck by the gross similarities between the skaven and the serpentmen of Yig that Lovecraft did write about in stories such as The Mound. There was also a pervasive sense of oppression about the book; the writer referenced frequently a seeming conspiracy to occlude and hide knowledge of the ratmen from mankind, most of whom even refused to accept that such creatures could exist. Many writers and/or artists who contributed to our knowledge of ratmen died or disappeared under mysterious circumstances; one was mentioned has having put out his own eyes after painting ratmen, supposedly from life models, although everyone believed him to be insane at that point, then joining a roving band of flagellants and never having been heard from again.
For those who are more than passingly familiar with the Warhammer world, not much in this book is really new information on the skaven. Although I've never played Warhammer, I floated around the fringe of the hobby for many years--most of the 90s, actually--and I bought many issues of White Dwarf magazine. Most of the issues between the mid-160s and... oh, I dunno... close to issue number 300. And I used to play lot of Blood Bowl. So, I certainly knew about the skaven; heck, I've got a team of Blood Bowl skaven converted from Warhammer plastic minis (in fact, my custom rat ogre is my favorite miniature of all the minis I own. It's a really well painted conversion, even if it's just me saying so. I need to take some pictures of it and post it here, don't I?) There is a seminal article in one of those older White Dwarfs (168, I think, if a quick google search of a White Dwarf index is correct) that explains much more about the skaven then this book does. Really, the only purpose of this book is to be an atmospheric study and an excuse to publish a lot of skaven artwork (including two by Wayne Reynolds that I'd never seen before.) I don't know that I can necessarily recommend the book for that alone, because it's a bit pricey as an atmosphere study, but it is an enjoyable one nonetheless. (For that matter, so was the Khorne portion of the Liber Chaotica--which also struck me as quite Lovecraftian in tone.)
Rather, the skaven--and the Warhammer world in general--strike me as a great example of what I want in gaming. Although ironically, I don't want exactly the Games Workshop variety of it, I find the tone and atmosphere that they manage to create most of the time to be right up my alley. Dark fantasy with really overt horror influences and strange Lovecraftian weirdness. Some of the novels even encourage this vibe; the Matthias Thulman omnibus (which I've reviewed here previously) for example are pretty good about it, and even feature skaven prominantly. The Felix and Gotrek Skavenslayer on the other hand, is too silly to ever be anything at all vaguely horrifying, and should probably be avoided. Taking something that most people consider loathsome and repugnant (such as rats--or as Lovecraft did, cephalopods and snakes) and making them malignant, vaguely anthropomorphic creatures that feature prominantly in the "secret history" of humanity, is a great idea.
And although the skaven aren't exactly obscure, given the success of the Warhammer game itself and several computer game iterations, some of which have also prominently featured the skaven (although Warhammer Online did not, sadly). But I think there's still room for someone to carve out a new take on the idea of ratmen. The old Sword & Sorcery Studios setting Scarred Lands gave us a fair take on the concept with the slytherin (no relation to the Harry Potter house, as far as I know), which also happen to be d20, and therefore compatible with my game. They also had some great Ron Spencer artwork in the old Scarred Lands monster manual, Creature Collection (which was famous--or perhaps infamous--for being released before the actual Monster Manual back in 2000, beating Wizards of the Coast to the punch a bit.) The Rokugan setting even has ratmen who are allies of humanity, and seen as noble savages. Huh? Anyway, I probably won't do much with that idea.
I'd like to incorporate the ratmen as the most populous inhabitants of my Forbidden Lands area, actually--make them a bit more like actual rats in many ways (although the wild mutations and insane experiments are part of the skaven's charm certainly, and I really struggle to not include some analog of the rat ogres) and take them a bit away from the familiar trappings of the skaven into something that's got a bit more of my stamp on it. Heck, I'd think Carcosa is their main city, and the King in Yellow maybe their god. I'd take away their Underempire and instead have their spies haunting the sewers and graveyards of humanity's cities; making them ghouls, first and foremost, who eat the dead, slip into homes to steal children, and--of course--spread plague and disease.
And, naturally, I'll have to watch Wilbur and Ben before I do anything with them, just to make sure that I'm on the right track in terms of feel. Yuck.