Finish and feel is good, better than the old canon lens or a YN. Optically good, probably on par with its old EF counterpart : center good and borders just a bit soft at f/1.8 on APSC. The autofocus is definitely not OK with mine, often stops besides the point and takes blurry photos ; you always have to check the focus in liveview and correct (manual focus is possible even in AF mode). Partly refunded, so the store handled it well. So, it's a good MF lens but not a good AF one!
quality is good. the focus engine is little noisey..