As I mentioned in another thread, I have this lens and love it. It's nice and sharp, and I've taken some great shots with it--in fact, I use it as much as I use my FD
50mm f/1.4.
I touched on this in the other tread, but it's probably more relevant here. I have two minor complaints--maybe concerns or reservations is a better word--with the Hexanon. My first is that you can't set the aperture to half-stops. In application, it's a stop slower than the FD 50 because I can shoot with great results at f/2 on the FD while I have stop down to f/2.8 on the Hexanon to get similar results.
The other concern is that at f/2.8 (the next notch down from wide open), the aperture blades have a funky shape, which makes for some funky bokeh when there are light sources in the background. The notches go mostly away at f/4. See this review
HERE for illustrations.
Again, don't think I'm dislike this lens, because I don't--quite the opposite, in fact. It's a great and compact lens, and it gets a lot of use on my G1. It probably will be a staple in my travel kit because of its image quality and compactness, whereas the FD lenses are very dense.
EDIT: I forgot to mention the part most relevant to this tread--I used the conversion kit sold on Ebay by Tai Chung to convert the lens to 4/3s. It worked fine for me and I completed the whole operation in an hour, though apparently some of the more time consuming steps are unnecessary having a fully functional lens.