This is a subjective issue. I voted 'watch it', based simply on a paper i wrote for my uni course in 2007.
I actually wrote the paper on the transformation that happens to books when adapted into film. I could send it to you for further analysis if you want. the general consensus to come form it was:
"Films therefore serve as superior medium for the introduction of an idea to a larger audience, and novels can provide further insight into these ideas. It can easily be argued either way, however, my predisposition is toward film, for I believe they can be far more provocative and as Persson stated, the audience is equally mentally stimulated by film as novels. Films bring the world to life, give identity and can enhance aspects of books; Donkey from ‘Shrek’ would not be as funny without his portrayal by actor Eddy Murphy, it is the actor which brings the character to life and reading a character like donkey without Eddy Murphy would unlikely be as entertaining. "
REFERENCES:
Corliss, R., Grossmann, L., Schickel, R., Lluscombe, B. (2005, November) Books Vs Movies. Time Magazine. Accessed Electronically 20 / 4/ 2007 via Google Search.
Ewing, R,. Simons, J. (2004) Beyond the Script: Take Two: Drama in the Classroom. Newtown, Australia: PETA.
Persson, P. (2003) Understanding Cinema: A Psychological Theory of Moving Imagery. Cambridge, UK: Cambridge University Press.
Stephenson, R., Debrix, J.R. (1969) The Cinema as Art. Harmondsworth, England: Penguin.
I would personally argue for two films as superior to novels: Fight Club and No Country For Old Men. The film versions of these are far more refined in story elements, equally thematic and metaphoric and inferential and overall entertainment value. When done right, films are better.
The argument can go either way, like my quote from my paper stated, films do things better in circumstances, books do others. Books have more content (generally) than film and more scope to develop the story, wheras a film is 2-3 hours finish (generally). But because i would recommend the unusual order of watching a film before reading the book, i think film is superior (generally, because everyone knows there's some bad film adaptations).