There were a lot of interesting ideas in Night Watch, with the basic one being the gray area that surrounds the actions of the Light Ones and the Dark Ones. Unfortunately, the book spends a lot of time not with convoluted plots that Anton, the main character, seems to figure out without actually letting the reader in on the process. The purpose of the whole mystery seems to change along the way and, well, I eventually just got bored of the plot twists.
The movie, on the other hand, was very interesting. It took the basic idea of the book, gave it far more purpose in a pithy manner and strengthened several other elements, including the main character and his purpose, to create a truly engaging story with an unexpected ending.
The film was, initially, rather visually chaotic, aiming, I assume, to shock and frighten. It helped that I’d read a few chapters of the book before watching, so that I could piece the chaos together a bit better.