You should note there is a lot of sample variation with the 100/zf re: focusing stiffness. I had one, and loved it. The images 'pop' into focus - very reminiscent of the 28/2,8 latest. However, I had to return it - the focus ring was intolerably stiff. The lens+adapter would rock back and forth in my 1Ds2 mount with the torque required to start focusing.
Talking to the retailer re: a replacement, they indicated they have received complaints of stiff focus on the 100 and couldn't ensure that I'd get a replacement that was any better as the few they had left from a recent shipment all felt 'stiff' to them. Bear in mind that while 'stiff' is a relative term, mine felt like it needed a CLA right out of the box. My 35/2 ZF is as smooth as silk.
With the shipping and VAT expenses buying into Canada from the US, I wasn't willing to start working that lottery, so I held off getting a replacement. As for buying local, it's laughable.
Like most of the ZF line, it does suffer from some CA on bokeh highlights, but nothing major. Also, the aperture ring sits in a narrow valley between the body and the start of the large barrel. It can make changing aperture a little cumbersome at first - especially with gloves.
My recc if you want one is to wait to buy until you can actually try a sample. Get a smooth one and it delivers great results.