Dennis Peter Bours , May 03, 2010; 11:56 p.m.
Photozone evaluated this lens:
It's surely a good lens, but the extreme corners only become reasonably sharp > f/5.6.
As work horse I now use the Nikon 18-35mm 3.5 - 4.5 (used mostly around f/11 for landscapes) and the Sigma 24-70 2.8 for any other type of shot. The Sigma 24-70 has good sharpness from f/4 onwards.
If you need a work horse on a DX camera, get the Nikkor AF-S 17-55mm f/2.8 G IF-ED DX. You'll find them second hand these days as well and they are surely worth the money. The sharpness is much better than the Sigma 17-70: