This movie has political undertones, but is very defintely not grandstanding. The story is told from a fact based point of view, and while the film is definetly taking sides, it does so without completely dissmissing the other point of view. Toward the end of the film, a major character questions whether he has been on the right side, or whether perhaps McCarthy was right.
You compare this to a film like "The Majestic," which I will admitt I really liked, but took a very heavy-handed, in your face approach making a hero out of anytone who was accused of anything under the McCarthy regime, and this is really quite fair and balanced. I also really liked the fact that this movie really wasn't about Hollywood blacklisting, which is all most film makers seem to care about when dealing with McCarthy.
Clooney is to be comended for telling a balanced a fair story, which certainly reflects his political beliefs, but does not distort the facts in order to support them.