Excerpt: This really is a great lens. I wanted something in the ultra wide range and this lens (at its current price point) is a steal. The build quality is great, very similar to L lenses. I would have rather purchased a 8-15 L however the price disparity makes the 10-22 much more attractive. This is only the case if you can live with an EFS lens though. I find myself leaving this lens on because it is just so fun to shoot with.
Conclusion: I use the 10-22mm f/3.5-4.5 USM mainly for waterfalls and small cascades in the mountains of the south east US. With a APS-C camera sensor this focal length is superb. While there is some distortion at the 10mm end for my purposes it is not objectionable. However, there is a fair amount of chromatic aberration. The lens produces fairly sharp images. The corners are less sharp. However, at this scale of image size details are small and it is not objectionable.
Pros: sharp images, nice contrast
Cons: not wide aperture, some chromatic aberration
Excerpt: I shoot video with a Canon 70D and this lens makes a great addition to my other lenses- Sigma 35mm f/1.4 DG HSM Lens, Canon EF 16-35mm f/2.8L II USM Lens and Canon EF 70-200mm f/2.8L IS II USM Lens. I would like the lens to be faster because I am often in low light situations but I don't think that exists- definitely not for this price. For the price, I think this lens is great. Wide, beautiful, good stuff.
Excerpt: I own a number of canon bodies and a dozen EF lenses. I'm a hobby photographer who relies on quality gear to compensate for my lack of ability. I've only used the 10-22 for a few shots but the non-fisheye, wide angle is fabulous for gathering the whole photo in close in settings. Typical canon quality. I do believe there is a bit of a fisheye bend at the peripheral edges noticeable in close in photos.