I read some more reviews and can't find any noteworthy flaws of the Canon 10-22. It seems to be everyone's first choice when it comes to ultra wide angle lenses. I would personally prefer the faster aperture over the broader focal range, but I guess compared to f/3.5 in the Canon lens, f/2.8 isn't enough of an advantage to take the risk of autofocus issues (reading about it in a review and also in your comment, Sean, kind of scared me off) and so-so image quality. Then again, I stumbled upon the Sigma 10-20 f/3.5 EX DC which seems like a good compromise to me. It has almost the same focal range as the Canon, but a fixed aperture, unlike the Canon. Is that one worth a try? Thank you for all the posts so far