I found this movie to be interesting and thoughtful, skillfully combining investigative reporting with art criticism and human interest. It was atmospheric and, perhaps most successfully of all, captured something of the allure that draws us to works of art and that then makes some people steal them--the latter a sort of perverse commentary on the intangible something about great art that makes us value it so highly.
By concentrating on the fascination that all the characters in the movie had with these paintings, the movie thus, for me, extended itself beyond the requirements of who stole the goods and how they did it (the theme, after all, of many tedious heist movies) and became an extended meditation on what it means to possess and be possessed by an image. Looked at this way, the movie grows in the imagination long after one or many viewings, and deepens very satisfyingly. Highly recommended.