I used to own one (Nikon mount). Excellent lens but works best if its stopped down to f11.
I didn't use the lens a great deal so I sold it. However, when I did use it the effect was superb.
Some things to be aware of... On the one that I had, the aperture ring was not linked to the camera, therefore as you stop down, the image in the viewfinder will get darker. Also, Nikon cameras with complex metering modes (such as those found on the F70), dislike this lens. You will need to switch from matrix metering to centre-weighted or spot metering otherwise the camera will display an error. This is one of the reasons why I didn't use the lens all that much... Changing the metering mode every time I used the lens on the F70 was a pain.
I have a sample image here:
Voigtlander Bessa R2A, CV lenses: 25/4, 35/1.7, 50/2.5, 1936 Leica 9cm f4 Elmar
Leica R7, 50/2 Summicron, 90/2.8 Elmarit, 180/3.4 Apo-Telyt-R
I'm not going digital... It's not photography, its computing!