Hi Dirk,
I've owned one in the past as well, so I'm reasonably familiar with it. So, even though I haven't yet had time to get prints back, I can tell you from previous experience that it's a nice lens. I was surprised just how sharp it is, it's impressive. There is some slight vignetting at f/3.5, but this is not surprising. From f/5.6 it seemed to be perfect if I remember it right! It has a yellow and orange filter built in for all you B&W shooters, and it is incredibly compact - even smaller than my Zuiko 21/3.5! I don't have the 40/2, but I'd guess that the fisheye would be a little bigger than that. Overall, it's up to the standard of the OM line IMO. If you can afford one, grab it!
Neil >