Is the Nikon 18-140mm f/3.5-5.6G AF-S DX VR Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 70mm f/5.6 test image. Observe the contrast and resolution of these results.
Is the Nikon 18-140mm f/3.5-5.6G AF-S DX VR Lens set to 70mm f/5.6 sharper than the Nikon 18-70mm f/3.5-4.5G AF-S DX Nikkor Lens set to 70mm f/4.5? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.