The Nikon has taken a lot from the big sister D200 - for example, the super sharp 2,5'TFT, fast autofocus, the large and very bright penta prism viewfinder.
Not much is missing to the multiple award-winning of the "sub-2,000-Euro-class" only in the magnesium housing, the X-contact for external flash units and smaller details (configurable in the menus, etc.) has been omitted. The rest is virtually identical in all aspects, and (semi-) professional what to 1,000 euros lifts the camera in the class at the very top.
The Canon 400D convinced really just at the point image quality and compactness. The feel of the case is not very good: the plastic seems cheap and the grip is just large enough to hold the hands of a 12-year-old. An adult man with normal-sized hands will in any case have little joy with this case.
What the 400D does a little better than the Nikon D80 is the shutter lag, which is shorter by the 12-16 ms according to various test reports than the competitors. In contrast, however, the Blackoutzeit is so incredibly short at the camera that you have the feeling that he had never left the scene of the eyes.
Another advantage of Nikon is the way the quality of the kit lens. While the 18-55mm lens the 400D is rather moderate sharply and tends to vignetting, so can be produced very decent pictures with the 18-135mm Zoom-Nikkor, even if the light intensity to the outermost end is easing (5.6). Overall, not bad, for as a low-priced (about 300 euros) and zoom strong part.
Bottom line, you can only congratulate Nikon idea to have on the Canon EOS 400D is a fairly good so strong response.
The Canon makes great pictures - no question. But handling and grip are designed but rather unfortunate. The Nikon masters all this with flying colors and also convinces with the much better viewfinder. You can obtain pictures perfectly compose.
From me 5 stars!