The following comparisons are not scientific by any means, but it's amusing -

http://www.pebbleplace.com/Personal/Medium_Format_Blog/Entries/2008/2/16_MEDIUM_FORMAT_VERSUS_CANON_AND_NIKON.html

http://www.pebbleplace.com/Personal/Medium_Format_Blog/Entries/2008/2/17_MEDIUM_FORMAT_VERSUS_CANON_5D_PART_II.html

I'll try to put some more comparison images during the next couple of weeks.

Here's a riddle for you, which is the 5D and which is the P25? Both shot handheld and some minor cropping to normalize the views.

There's no doubt in my mind that the P25 was superior in terms of image quality. If the images are printed at large sizes, then the quality is realized. If the medium format image is downsized, then the advantages are diminished. In the downsized pictures I still see more detail in the medium format images, but that is subject related. In a landscape they don't look much different. In a product shot the P25 show more detail. In the landscape the eye picks up on the total scene. In the product shot the eye wanders and start to focus on tiny details/areas.

In terms of DOF & FOV; 35mm dSLRs can't match that. That's is an inherent part of the "medium format look". dSLRs can hedge their bets and shoot with faster lens (minimize DOF), but they still have to shoot with wider lenses. A 50mm portrait vs a 80mm portrait will have different compression, thus a different look. Now that Phase One has the P65+ with its new 40.4 X 54.9mm sensor, I think people will really begin to notice the "medium format look". The 48mmx36mm sensors had the look to the degree, but I expect the Phase One P65+ to really capture the feel of the old film negatives (in terms of FOV & DOF).

Here's a preview to the P65+ Luminous-Landscape Phase One P65+ Preview.