This has always been my least-favorite of the series, mostly because it's a little slower, more plodding, without the great character development of the rest of the series. But then I read it yesterday and thought about it in light of the revelations of Book 6, and you know? It's not so bad. There's a lot of information in there that's really useful. So this isn't a slow, boring, "filler" book, but rather it's a set-up book--weaving in bits that will be really useful later. 
 It's still not my favorite, though.