The Game of Thrones finale was this weekend. If you don't want to be spoiled, just stop reading now.
There's quite a lot that I don't remember from the books - the last things I could think of were the fight between The Mountain and The Viper with the attendant poisoning, and Tyrion shooting his father on the chamber pot. I don't think there was any ominous foreshadowing about the post-poisoning process making Gregor Clegane stronger, and I certainly don't recall Tyrion strangling Shae - I thought his father had her killed.
After this, it's all a blur. I remember Tyrion going overseas, Cersei going insane, Arya going to Braavos and joining some weird blind brotherhood, Mance Rayder being hanged, and Dany doing nothing for about three books. Mostly, it's just everyone sitting around doing nothing.
I barely remembered Stannis helping at the wall. I didn't remember the fireball-throwing "child" at all. I did remember the dragon killing a child. But when Sandor Clegane and Arya bumped into Brienne and Pod, I was caught off guard. I couldn't remember what happened to either character, so I had no idea who would win. I'd have put my money on The Hound. I'd have been wrong. Looks like Brienne is far more badass than I'd have given her credit for. The only ones I'd say that could beat her would be Bronn, Jaime when he still had both hands, or Gregor Clegane while he was still vertical. I guess I'd also give The Viper a chance given his impressive showing against The Mountain. Maybe Loras Tyrell, maybe Sir Arthur Dayne, but I'm not so sure. It's fun to muse about ridonkulous questions like this which only have answers in the mind of an author.
The Brienne/Hound battle doesn't happen in the books; they don't even meet. The Hound's infection spreads until he's too weak to move, and he pretty much pleads with Arya to kill him but she does not oblige.
The Mountain's condition is more or less hinted at a couple of times, but I don't recall too much in the way of specific scenes that reveal what's really going on. Rather, if I recall correctly, Maester Qyburn spends a considerable amount of time and effort trying to save Ser Gregor, but to no avail. The Mountain's head (or so it seems) is delivered to the Martell's as proof that he is dead, but we get hints that Qyburn is up to something. I suspect the TV series is going to play up the Frankenstein's Monster angle on this a bit more than the books do.
Cersei doesn't so much go insane in the books (depending upon your definition of insanity) but she does wind up having a very, very bad stretch of time where she sees everything she's worked for fall apart around her. She does have some glimmer of hope near the end of "A Dance With Dragons," having found a mysterious new champion (a large—some might say mountain of a—man whose face is concealed beneath a helm, and who never speaks) courtesy of Maester Qyburn.