The 10-22 is a very good lens and is the crop camera's equivalent to a FF 16-35. For crop ultrawides, it's really a pick between the 10-22, the Tokina 11-16 and the Sigma 8-16. All three are good choices, and each has it's strengths. If you want the widest, get the Sigma. If you want the largest aperture and the sharpest corners, get the Tokina. If you want an all around good performer, get the Canon. The Tokina has a larger aperture and is a little sharper at the edges than the Canon, but it's focal length range is limited. The Tokina tends to be favored for architecture. I find the overlap range (15 to 17-22 mm) really handy because it minimizes lens swaps. To to take a picture of a room or a scenic vista, use the 10mm. To take a group picture, use the 22mm range. The 10-22 also has the largest maximum magnification ratio of 0.17 compared to Tokina's 0.09 and Sigma's 0.13, which helps for closeup shots.