I've only read the first 2 and half the 3rd so I'm aware of a lot of the characters that have been cut. I quite like that they're splitting away from the books in the show because it does give it more intrigue, however, the show version of events often come across as less thought out. Not a big surprise considering GRRM has spent the better part of 30 years writing and refining. David Benioff and DB Weiss have only been at it for like 5 years now.