Welcome to the forum!
I bought my EF-S 10-22mm lens long before the EF-S 10-18mm was announced. The latter is a lower-cost option, but I have no regrets, as I find the full range from 10mm to 22mm to be very useful. Notably, the 10-22mm has less distortion than the newly-announced EF 16-35mm f/4L! (I still plan to acquire the 16-35/4L, a funds allow, to use on my larger-sensor Canon cameras that cannot function with EF-S lenses.)
Any lens wider than about 28mm will require careful attention to holding very level, along the front-to-rear axis, when shooting, to avoid vertical lines, such as buildings and trees, leaning inward or outward. Even the best wide-angle lenses will show this characteristic, which is independent from lens-induced barrel distortion.
As already stated in other posts, barrel distortion can be corrected, either in post-processing, or in-camera, if the camera model has the ability. More importantly, proper composition can minimize the effects of distortion, or use it creatively. Notably, moderate barrel distortion is not usually noticeable in natural landscape images, being more of a concern for urban landscapes and city-scapes.