Go see it. It's good, and important.
What's up with Clooney's political movies lately? This one, like Good Night, and Good Luck, is very good. The difference lies in the complexity: Good Night is very simple and straightforward, but Syriana is almost baroque in its complexity. It's the kind of movie that I think you'd have to see several times to catch it all. I know I'll have to. Even the first time, though, it's gripping and has a great plot, but the central idea-- oil-- is written all over every scene. Everyone's lives in the movie are shaped and dictated by the struggle for it, some in interesting ways.
It will definitely make you think the next time you stop at the gas station.