Not too many people buy the ZF version, since the Contax version is nearly identical and is available for half the price or less. I own the Zeiss (contax mount) 50 f/1.7, which is somewhat sharper than the f/1.4 (though probably insignificant in daily use), and it is extremely good. Very, very sharp, and much sharper at f/1.7 than the Canon 50 f/1.4 is at f/1.8. By f/4, it's probably the sharpest lens I've ever used. In fact, it's TOO sharp and contrasty for portraits. I use a Pentax (screwmount) Super-Takumar 50 f/1.4 for my portrait needs, as it's plenty sharp enough, with nicer bokeh, and a much smoother contrast curve, which is better for portraits. The Zeiss, I use for non-people subjects, where it really excels.
A recent shot from my Zeiss 50 f/1.7:

Now, my Contax mount Zeiss 85 f/2.8 Sonnar is simply spectacular. Incredible color, great contrast, insanely sharp, but also renders pleasing skin tones. It's one of my absolute favorite lenses. Let's put it this way: I like it better than the 135L that I used to own. I got mine for $230, but the price on it seems to be climbing, with copies on eBay going for between $300 and $450.
A shot from my Zeiss 85 f/2.8, wide open: