Is the Canon EF 17-40mm f/4L USM Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 40mm f/11.0 test image. Observe the contrast and resolution of these results.
Is the Canon EF 17-40mm f/4L USM Lens set to 40mm f/11.0 sharper than the Canon EF 24-70mm f/2.8L II USM Lens set to 24mm f/3.2? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.