Finished "Gerald's Game", which I remember reading in November 2003 when I was 17, at my cousin's house on Thanksgiving, felt awful, had been doing coke everyday, and was just worn out and a mess. I went into his room and found this book and read the whole thing that afternoon, which was disturbing and strange on top of everything else, but captivating.
I think the adaptation worked very well, hard to to watch multiple times towards the end, visceral reactions to the cutting. I think Flannagan's direction is a little flat and sterile, but he's very good at this. I don't know about the dude snapping off the cuffs, I was waiting for her to wake back up in the cabin. I remember the book being a lot more detailed about Gerald's abuse and power control issues, but it's been like 15 years since I read it, may be time to pick up a copy.