Is the Nikon 14-24mm f/2.8G AF-S Nikkor Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 20mm f/11.0 test image. Observe the contrast and resolution of these results.
Is the Nikon 14-24mm f/2.8G AF-S Nikkor Lens set to 20mm f/11.0 sharper than the Zeiss 21mm f/2.8 Classic Lens set to 21mm f/11.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.