I will publish my opinion, although I'm not an expert.
I'm really impressed so far with the 2808. It replaced my old DENON AVR-1602. Since I use the same speakers, I was very impressed, the sounds are so much better now. All music types (Jazz, Classic, Rock, Electronic) sounds better on the 2808 (no big surprise though).
I also bought the DENON iPOD dock and I love using it, I browse my iPOD (iPOD classic 80 GB) and can see the display on the receiver or/and on the TV. I just put the dock behind my plasma TV so I don't even need to see it. I am in the process of transferring all my CDs to the iPOD for easy listening (I know the format loses quality, but who cares? no CDs in the living room!!).
Watching a DVD on a 1080i upscaled picture from my Philips (DVP5982) was great on my Pioneer 43" Plasma. I compared the DVD Movie shown through the Denon to the one show when the DVD is connected directly and I liked the Denon better, it was more crisp.
HDTV (1080i) looked the same when connecting through the Denon or directly to my screen.
PS3 had a great picture and sound, so did my Wii (I know, I just love those things..).
The remote is very nice to look at , but the input sources buttons (bottom part of the remote) are a little confusing. It might be because my old model is 6 years old, but I think the interface is not the best, Some buttons have two functions (for example DVR/VCR) so you press them twice to get to where you want and button number 2 is for XM although its label doesn't say so.
Anyway, I just installed it yesterday, and I still have a lot to work on, but I enjoy my 2808 so much for now!!