Best AF UWA in terms of sharpness and color / contrast for canon mount at the moment. It beats the 10-22 from Canon. Two of my friends bought it and I had lots of time to play with it over a few weeks. It's drop dead gorgeous.
I didn't sell mine even though I need some funds to buy the 85mm lens although someone offered me a price that is near to my purchase price. It is a keeper! Sharper even compared with Nikon 12-24mm DX Lens!