In the middle of a my first roll with one I just picked up. The build quality is higher than I expected and I've seen great results from others with the lens. Figured I'd buy one now before someone starts taking brilliant photos with a 75 and the prices skyrockets.
This lens is typical for Heliars...excellent gradations and amazing color, (if you shoot color at all).
I'll let others speak for its outstanding B+W performance and you can check out the full description at Cameraquest.com.
I don't do colour, no. I've read a lot about this lens (also the cameraquest sales talk ) but it's not always easy to hear actual users about specifics that interest me. These days it's mostly about colour and sharpness on M8, M9, NEX, MFT etc.
The general impression that I have of CV RF lenses is that they are rather high in contrast, and therefore not so nice for b&w (in my highly subjective opinion). I'm often wondering to myself if there are any exceptions to this 'rule'. The 35mm/1.7 Ultron is pretty smooth for example.
I was hoping to hear some first hand harsh-smooth talk about the Heliar. But if you shoot/shot colour mostly then you probably wouldn't know. Thanks anyway and good luck with the sale.