They did get some things right for sure. And some of the changes were pretty cool (like H's avatar). If It were up to me I'd add 30 minutes of details and the puzzles from the book. perhaps have the car race lead to the D&D cave and then the Joust duel? I really wanted the Joust duel either as a video game or them actually jumping into the video game and flying on the ostriches. That would have been really funny. Oh well.
It seems that people that haven't read the book really enjoy it. That actually helps. So now I have my joy of Ready Player One form the book and they have it from the movie.