Is the Canon EF-S 10-22mm f/3.5-4.5 USM Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 17mm f/4.0 test image. Observe the contrast and resolution of these results.
Is the Canon EF-S 10-22mm f/3.5-4.5 USM Lens set to 17mm f/4.0 sharper than the Tamron SP AF 10-24mm f/3.5-4.5 Di II LD Lens set to 18mm f/5.6? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.