Also give it a C+ Ok, but not spectacular.
I found it kind of annoying that the whole thing was sort of a "look the Monuments Men are at St. Lo, Remagen, Bastogne..." Like, what, audiences could not follow the story if you didn't put the Remagen bridge in the background with CGI? And what paintings were in Bastogne?
They could have told the story much better... because it is a great story. I think Clooney just sucks as a director, for one thing. Contrast this movie with Three Kings, which had a similar plot line (and Clooney) and see a much better story, dialogue and continuity. This wasn't a bad story or even bad acting. It was bad directing.
Just my 2 percent of a dollar... YMMV, as seen on TV, etc.
Cheers,
Sirhr