Is the Nikon 70-300mm f/4.5-5.6G AF-S VR Nikkor Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 300mm f/8.0 test image. Observe the contrast and resolution of these results.
Is the Nikon 70-300mm f/4.5-5.6G AF-S VR Nikkor Lens set to 300mm f/8.0 sharper than the Tamron 70-200mm f/2.8 Di VC USD G2 Lens set to 400mm f/8.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.