Well, you don't get something for nothing. This lens is decently made, handles nicely and has good image quality when stopped down. But it's going back to the dealer. Perhaps I had a bad sample, but it's simply not very good at wide apertures, and that's the whole point of a fast prime to me.
I've heard complaints about Sigma's two-step manual focusing, but I found this to be a plus as the focus ring feels like an honest-to-god manual focus ring with positive stops at both ends of its travel. The auto focus is a bit loud, but I would have lived with it had the imaging performance been better.