I finished A Clash of Kings (Book 2) a week or so ago and I’ll be starting A Storm of Swords shortly. I’m enjoying the books, but they’re not the best I’ve ever read. My biggest complaint is the over-use of profanity. I’m no prude and have no problem with profanity being used when appropriate but it seems to me that GRRM just puts it in because he can. I feel the same way about graphic descriptions of sex acts. If they fit the story, fine, but don’t force them in.
I think that there’s a bit more going on behind the vulgarity. With the exception of Tyrion, many of the protagonists are pretty much vulgarity-free. I think that he uses it to demonstrate characters who have given up on the value of social graces and of bettering society, and are existing purely on self-preservation.