Zodiac: 8 out of 10.
David Fincher directed "Seven" and "Fight Club", so we know he's got the chops. "Zodiac" is a completely different kind of film but equally compelling. I enjoyed it, and I rarely enjoy any film longer than two hours. "Zodiac" is closer to three hours than two.
It's a big cast of actors you already like and the subject matter is intriguing. This is the film I thought Spike Lee's "Son of Sam" was going to be. It's got a wonderful "All the President's Men" feel to it. Fincher should be proud.