I received this as a birthday present and was eager to try it out. The first thing I noticed was that the AF didn't seem to be working. After switching back and forth between AF/MF the lens eventually started working. Obviously not a good start.
But the speed of the lens and the sharpness of the images was quite good. I would not have thought the lens to be so cheap for the quality I was getting.
However, after a week of use on my 20D, I've found that I've had to move back from subjects in order to fit them into the photo. I would be very much interested in using the Sigma 30mm F1.4 HSM on a 1.6x camera.