Book 4 is where people feel that the series falters. But I do not.
It's true that there are less swords stuck into throats and crotches in book 4. But we don't read books to see swords stuck in crotches (that's what we watch TV for... all that wonderful crotch swording action). We read books for dialogue, character development, a look into a person's psychology during dramatic events, etc. And it doesn't waver in this regard. GRRM's style remains just as strong as it has in the other books.
Book 5 does annoy me a bit in a few places. But worry not, plenty of swords are stuck in crotches in that book.