I love this lens!  It's my favorite lens thus far and my primary lens for most occasions.  I got it for the depth of field capabilities and couldn't be happier.  It does well in low light situations and is wonderful for macro and portrait shots.  I love the control system for manual focusing.  I don't generally use auto-focusing but did try it and it works ok.  It was a little slow when I tried it but not much of a problem for me since I don't really use that feature.  Images in the focus point are crisp and everything else has nice smooth bokeh.  If you use f-stops below f3.5, the depth of field is really shallow so be careful to get your focus point just right or else everything will be out of focus. 

Question: Is the focus ring smooth?
Answer: the focus point are crisp and everything else has nice smooth bokeh