It's a very nice lens. Unlike Paul, I find it to be a noticeably low contrast lens—especially compared to the CS 35/2.5 or the 28/3.5 (the former more so than the latter). I took it out street shooting and did_not_like the results, but I have my workflow/processing tuned (for lack of a better word) to the 35/2.5 and the 28/3.5. It's a tad on the big side, too.
I'm still trying to find a use for a fast 28.