I've been using Canon DSLR's for the last 4 years - a Canon 5D for the last 18 months or so and have recently bought a ZD (camera - not back). I've just returned from my first shoot with it and my thoughts are very much in line with Frank's.
While away in the bush, I'd noticed the greater depth or '3D' effect while reveiwing images of the same subject taken with the ZD & 5D on my laptop, so was interested to see Frank report the same thing. I don't know what the reason is - I don't think it's due the the shallower DoF, but whatever it is, I like it.
Feppe, there is good and bad in the comparison of usability between the ZD and 5D. Generally the ZD is very easy to use. For Canon users the MLU is brilliant! The buttons are well laid out and logical. Autofocus is fast and very accurate, though I found myself using manual focus most of the time - I generally use AF with the 5D.
But there are some real quirks in the menu and image review area. As Michael pointed out in his review, the menu system is very 80's and could be made to be much better with a bit of expertise. Having said that, once you get used to it it's not hard to find what you're looking for.
As widely reported the review screen is so small as to be almost unusable. Additionally while you get a histogram and flashing overexposure (and underexposure if you want) warning with the initial review image, you cannot get either if you call up an image later from the card. You only get the image itself. Also, if you set the review to display histogram & flashing highlights, the image is so small that you can hardly see the flashing highlights anyway. This area badly needs improvement.
This along with speed of image review and writing to the card are the areas I would like to see improved.
Despite my criticisms, I've absolutely no regrets about having bought the camera.
In addition I was amazed at how easy and cheap it was to assemble a good range of Mamiya lenses. Apart from the 35mm, which is just OK, they're excellent.