I absolutely love this series. A friend of mine got me watching it last summer and knocked out the two seasons in around 72 hours. Started reading the first book immediately and am now a little over halfway finished with the 5th book (ADwD).
I won't spoil anything for anyone, but all I'll say is that for those of you who don't know what happens after season (or book) 2, you better buckle up, because you're in for a wild ride... And that is with the 3rd book being broken off into two seasons. So many memorable scenes in SoS.
SoS is possibly the best book I've ever read, period. The 4th book (AFfC) is probably the worst one in the series so far. Not that it's bad, but I thought GRRM got way too detailed with characters and stories that frankly I don't really care about. I'm sure it'll all tie together in some way though, with the last two books still to come. But I didn't get much out of AFfC until the last 100 or so pages, and I really enjoyed those (for obvious reasons, those of you who have read it).
Tyrion is probably my favorite character. Peter Dinklage does an outstanding job portraying him, but I enjoy Tyrion's passages in the books even more. I've always had a soft spot for Bran and Arya as well.
When I finish the ADwD, I'll definitely be stopping by the spoiler thread...