I walked out of it after about an hour in. The VFX and 80s nostalgia was cool for a bit, but the movie was lost on me because of how different it was from the book. I really enjoyed the book, and I wasn't expecting the movie to follow it 100%. But I was hoping that it would hold tightly to the book.
All that said, if you haven't read the book definitely go see it. The dialogue is painfully weak, but the VFX will make up for it if you're into that kinda thing.