I own about 10 lenses, including 4 Canon L lenses. This is my best lens by far. The rendering is sublime, the build quality is excellent, the sharpness wide open blows my mind. It's hard to put into words how good this lens is.
I don't really like the 50mm focal length. I sold two other 50mm lenses I tried because the focal length, for me, is neither here nor there. 50mm isn't wide enough to be a good general purpose environmental lens, and it's not long enough to capture subjects farther away. Even with that said, this is the lens that is glued onto my camera 70% of the time. The image quality is sublime at all apertures, and it's just fun to use. I even use it sometimes for product photography over my 100mm 2.8L when I can because I just love the rendering so much.
Cons are the price, and the weight. But I think it's absolutely worth the price, probably more actually. And I'm a large guy so personally the weight doesn't bother me, but I could see it being an issue for some.