The Nikon 24-85mm ƒ/3.5-4.5 VR provides generally quite sharp images. Performance is better when the lens is mounted on the sub-frame (DX) D7000, as the lens' corner performance is not seen by that camera's sensor.
Used wide open on the D7000, images are almost tack-sharp, with just a hint of corner softness at the 24mm focal length. Zooming to 50mm or stopping down even just a half-stop solves this problem and you're left with super-sharp images. The 70mm and 85mm settings aren't as sharp, though it's just a matter of degrees; performance is still excellent, though curiously, it's slightly better at 85mm than at 70mm.
Mounted on the full-frame D800 exposes the lens' true nature. Used at the widest aperture setting at any focal length produces some level of corner softness: from considerable at 24mm, to just slight at 85mm. Central sharpness is very good when used wide open, and gets somewhat better when stopped down to ƒ/5.6 or ƒ/8, but you don't get the same tack-sharp images with this lens when used with the D7000. In this case, we could be seeing the sensor out-resolving the lens.
Diffraction limiting sets in by ƒ/11, though the effects are really noticeable until ƒ/16: fully stopped-down performance is generally best avoided, as it produces consistently average performance.