I just got this lens and have been impressed. There is no obvious light fall off, vignetting, CA, distortion, etc. The following photos I shot with D200 and only resized for the web and minimally adjusted levels. Camera was default Normal settings. Sigma did a good job on this lens. Wanted to show the difference between 10mm and standard 12mm, and between 10mm and 18mm, quite a difference.
Remember, it's cold and drab outside this time of year, so not as colorful in the Dock scene