This is what a movie adaptation should be. Lots of background and descriptions, not a scene for scene, shot for shot regurgitation. There are a few differences from the film, probably last-minute production changes made after the script was sent off for novelization.
In fact, it has some changes in it that I remember being "wrong" when reading the comic book many years ago.
Quick read. Excellent.
This book is the Gold Standard for movie adaptations, along with Star Trek II: the Wrath of Khan.