Hi, I recieved my Sigma EX 24mm/1.8 just today. I can't comment on the optical quality yet (other than no distortion visible), but the mechanical side could be better. Focusing from 18cm to infinity in a quarter of a twist takes getting used to since I use only manual focusing gear. The focus is dampened pretty well but there is some play with it and it has a whirring noise to it. Well I guess most AF lenses do this when focusing in MF. But still: yuck.
IŽve read good things about the quality of these 20,24 and 28mm EXDGASPMACRO :) Sigmas. Only thing concerning me is flare, but IŽm sure this lens doesnŽt flare nearly as much as my Tamron 24mm/2.5 did. If I only had a FA* 24mm/2 to test the Sigma with... Guess IŽll upload some sample pics in the coming weeks. -mte