I borrowed a friend's D80 a few days ago and was experimenting with it. I found the controls to be mind-blowing, as there were so many of them and they weren't marked in any way that I found meaningful (having not seen the manual, which he didn't have with him). Far from enjoying all the AF points I was trying to turn all bar one off, as I wanted to photograph someone through slats and the damned thing kept focussing on the slats. I'm sure there must be a way, but I couldn't work it out and he didn't know (he used the camera like a P&S).
He had Nikon's 28-200 zoom fitted, and I have to say that I thought it was a horrible lens to use. Because I couldn't do what i wanted with AF I turned it off, but found the very thin manual focus ring to be difficult to hold (impossible with gloves) and jerky in its movement. I gave up trying to focus accurately with it. I also wasn't very keen on the zoom, as it didn't move linearly but seemed to "change gear" about half way towards the telephoto end. It was smooth in its action but still difficult to use precisely. My Canon 100-400L has a push-pull zoom so that's not comparable, but the focus ring on that lens, and on my 24-105L, is beautifully smooth and easy to grip even with gloves on, as is the rotating zoom ring on the 24-105. The Canon lenses feel vastly better made, though I didn't see any results from the Nikon lens.
I was initially a bit surprised that on the Nikon lens the focus ring was close to the camera body and the zoom was at the business end. Meant that I HAD to remove the lens hood from it's inverted "stored" position to use the lens at all, unlike both my Canon zooms (and all the FD lenses I have at home, from several manufacturers).
All this talk about Nikon's sophisticated AF compared with Canon's rather primitive offering (!) ..... I generally turn off the AF points on my 5D, and use just one on the main subject. Allows me to be far more creative.
In any case, Canon are saying that the 5DMkII doesn't just have the AF points you can see (I forget if it's more than the 9 of the Mk1) but that these are only the ones you can control. They say the whole image is covered with AF points that the camera sees but you don't. I'm not sure I understand that, but if I do then it means that my strategy of choosing one point I want to be in sharp focus won't work with that camera, and I don't like that.
From what I've seen so far I won't be buying the MkII, and in fact I can't see any other Canon DSLR I want to buy. I'll keep my Mk1 and my two L zoom lenses and probably add a fast 50mm and maybe an UWA zoom, but that will be it.
My next camera based on what's out there today will certainly be a Nikon, probably a D700 or a D3. I won't buy a D3 until the price drops quite a lot, as I think it will, and even then possibly not just because of the sheer size of the thing. Nikon seem understand that it's the quality of the pictures you take that matters, not a detailed check-list of merit points. These two Nikons will take superb pictures in low light very quickly, and that'll do me. But I'll need to choose the lenses very carefully, as none of the Nikkor lenses I've used recently impressed me with their build quality or ergonomics.
I'm an enthusiastic amateur who's published a bit (back in film days, using my much loved A1) and I want the quality of pro kit but not the bulk and probably not all the gongs and whistles. I know lots of amateur photographers like that, so I expect the D700/5DMkII area of the market to become very important and competitive. I just wish Canon had done a bit better with this most important upgrade - it isn't enough to stop the trend towards Nikon.