Mines going back because of an AF issue, it just stops AF'ing and I have to reboot the D300 to get it going again. Although that is with the Nikon AF system so I don't want to put you off. Another note on AF is that I find mine hunts an awful lot even in moderate light. In terms of sharpness I find it's ok but not quite as sharp as I'd hoped even at f8-f11. Can't be beaten on price though....