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 17mm f/8.0 test image. Observe the contrast and resolution of these results.
Is the Canon EF 17-40mm f/4L USM Lens set to 17mm f/8.0 sharper than the Canon RF 14-35mm F4 L IS USM Lens set to 35mm f/5.6? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.