I don't think they can really be compared to the medium format Zeiss offerings for Hasselblad or Rollei. As I said earlier I agree flare control always seems a step above the rest when it comes to anything with T* coatings.
I'm a 100% film user. Don't own any digital equipment. My gut feeling with these lenses was always that Zeiss assumed many people would use them with digital, and that many of those people would be using digital cameras with smaller sensors than full frame, meaning they'd have a sweet spot advantage since they aren't using the edges of the image circle. Zeiss also paid alot of attention to bokeh, which is useless to me, although others might value these qualities for shallow depth of field photography etc.
So Zeiss kind of slacked off on the edges and corners with some of these, in particular the 25mm, which I was most disappointed with. It has a significant amount of barrel distortion too. I was never thrilled with the 24mm Nikkor offerings so I was initially really excited when the 25mm ZF came out. Big let down. Why don't any of these expensive Zeiss lenses have precision ground aspherics for example?
The 50mm 1.4 planar? Forget it. My lowly Nikkor AF 1.4D is every bit as sharp and contrasty, just as well corrected, and has slightly less distortion. The Planar probably has the edge on flare control in backlit situations etc, but to me a 50mm lens that expensive should, for example, have imperceptible distortion.
The 35mm f2 is quite good, and sharper around the edges than my 35mm f2 AF-D Nikkor, but the Zeiss has noticeably more distortion.
The 21mm is also quite good. It looks very sharp to me all the way to the corners though it still has too much mustache-style complex distortion for a lens that price (there are some newer wide angle Nikkor zooms that have negligeable distortion at focal lengths like 21mm and 24mm).
Those are the 4 I own. I didn't bother with the 85mm because the two Nikkors I have in that focal length are razor sharp and distortionless. Some have suggested the 50mm f2 makro is an excellent lens, but it's way too expensive for me to consider.
I just don't think they are all they appear to be when you look at them and feel how solid they are. Just not worth the money from an optical perspective in my opinion.