I didn't like how they portrayed him in the second movie novel. They got rid of any moment where he showed some humanity like in the movie when he was horrified by mangle tearing Alex apart, or how he genuinely looked emotional after Vanessa rejected him. They got rid of that and made him purely evil like his father which I don't think is as good a character as in the movie when he was TRYING to be like William but didn't have it in him.
Also how Vanessa sees him is different in the novel. In the movie it seemed like both siblings still felt some kind of connection and longing to be together again whereas in the novel Vanessa felt disdain towards him and said she couldn't even look at him when they were younger, and Michael's moment where he asked her to come home was purely an act in the book. In the movie he seemed to have a genuine emotional crash out. Vanessa also thought that maybe he never resisted William and was always gonna be as evil as their dad ("a chip off the mad block") which completely ruins the idea that he's just abused and manipulated. Yeah I didn't like the novel apart from when it called him good looking.
There was one moment where Michael showed fear after being chased by the marionette-possessed Lisa and found it shameful. It suggests he's been abused and heavily manipulated but I don't think that makes up for everything else they changed. They made him sadistic and enjoy watching/listening to Alex being torn up. They made him more of an asshole towards Vanessa. They just made William 2.0 which is boring.