I appreciate good glass regardless of the name, but invariably when I try Zeiss lenses, I tend to like them more than other brands, on average. It probably has to do with the threedimensionality and the way the in and out of focus passage looks through their lenses. A uniform colour rendition and superb sharpness are just the final icing on the cake.
Take a look at the 35 Biogon shot I've just uploaded now - this is close range rendition that makes your head spin:
http://www.flickr.com/photo_zoom.gne?id=1240549537&size=l
and this one is how it looks like at infinity:
http://www.flickr.com/photo_zoom.gne?id=1217248456&size=l
Consider these are handheld shots taken on XP2, I wonder how they'd turn up on a good 100 ISO silver film...