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 10mm f/5.6 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 10mm f/5.6 sharper than the Tamron 10-24mm f/3.5-4.5 Di II VC HLD Lens set to 10mm f/3.5? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.