Is the Nikon 70-300mm f/4-5.6G AF Nikkor Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 300mm f/6.3 test image. Observe the contrast and resolution of these results.
Is the Nikon 70-300mm f/4-5.6G AF Nikkor Lens set to 300mm f/6.3 sharper than the Nikon 70-300mm f/4.5-5.6G AF-S VR Nikkor Lens set to 200mm f/5.6? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.