I watched this last night and overall it was a better than average thriller--the characters are better developed than what you might usually find and the acting is good. However, the film is ungodly LONG. 2 hrs and 40 mins of the Zodiac killer. The film is not poetic in the least and so it is all straight forward plot/action, but man, I got to about an hour and 40 mins and was still shocked I had an entire hour remaining.
It's not that it gets boring, but it really should not be this long. Really.