The colourized version is amazing. But quite aside from that, I think this film (colour or B&W) is actually quite underrated. Sure it's hugely popular, but it's still widely thought of as a mere Christmas movie. Few film buffs would think to put it on a par with, say, Sunset Boulevard, which came out just a few years later. I'm not so sure. IWL may get looked down on because it has a kind of Norman Rockwell feel to it, and Clarence the angel is kind of silly. But what makes this movie great is the tremendous inner tension that Jimmy Stewart brings to the hero, George Bailey. Oh, George does the good boy thing and stays in Bedford Falls year after year for the good of others but the sense of sacrifice and inner conflict are always there--at least until the very end. That's what makes this movie endure while more traditional "Christmas" films like "White Christmas" and "Miracle on 34th Street" fade away into film history.