It’s never boring? Maybe if you need a lot of explosions you might find yourself nodding out. It just doesn't develop characters and sort of lacks drama. You do not get a sense really of who these people are. Bill Murray is Bill Murray no matter if you show him up on a Chicago scaffold for a few seconds. Bob Balaban is pithy and has some funny lines but who he IS, as a character, is something of a mystery. George Clooney is a movie star and a great actor. He can do action, drama, and comedy. But here he, while he isn't bad, his role is just not memorable. The only actors whose characters come to life at all are Matt Damon's James Granger and Cate Blanchett's Claire Simone. They seem human, you care about them. This is in part due to there being enough personal interaction between them (and between them and other characters) that you get more of a sense who they are.
This scene brings up another problem with the movie; who are the bad guys? Are the bad guys the Nazis in general? The SS officer who presided over the massive thefts from France is one villain. Another villain is a different, more murderous SS officer. Then the Russians are brought into the mix (and to be sure when the Russians came across art they were not big on trying to get it back to the original owners). For the sake of a film it might have been better to pick ONE--even if it was an amalgamation of different characters.
The film moves along nicely but, as noted, the drama that should be there is not. It may be that it is all played a little too light-hearted for the subject matter. It skates past truths like the fact that the American demolition of Monte Casino was totally unnecessary (the Germans were definitively NOT using the monastery itself). This is mentioned in the film? If you mention it? Take 30 more seconds to explain what happened and they knew at the time because they covered it up, blaming the destruction on the Germans.
It isn't really a history lesson that some of the "Its BORING history" folks are saying. As an aside, if you say "history is boring" you should just add "I am a moron" because history is everything. History is last year's Super Bowl. History is your parent's wedding anniversary. History is also wars, politics, entertainment and everything else that has ever happened. If that bores you are clearly a moron.
This isn't history. It barely even tries to be and that is something of a shame. If it had paid more attention to the details of history and been a more personal movie instead of an ensemble one it might have worked. Clooney is a talented director as shown in films such as Ides of March and Good Night, and Good Luck. But this one got away from him a little.