I was skeptical at first to buy a Sigma lens for my Canon EOS 7D. But now I am a satisfied customer not only of this lens. The free processing like making a professional impression. Good solution I find the handling of the lens cap and the Streulichblende which belongs together with a pouch. Luckily I stayed probably spared the described back and front focus issues. Also, I can not centering etc. notice. In direct comparison with a Canon 10-22 / 3.5-4.5 USM, the Sigma does not have to hide. At full aperture the Sigma is even slightly sharper in the center of the image. Unfortunately this takes focus to the outer edge to the level of the Canon lens. The chromatic aberration is at the Sigma but a more pronounced in strong light. In my experience the Objetiv already from aperture 4 a very good imaging performance which is more than sufficient for the ambitious amateur photographers. Since June 2010 I have the Sigma in use and am very satisfied with the lens. It gets me all 5 points!
