I picked a 820 yesterday. So far I am liking it a lot, nice upgrade from the 900 IMO. :)
I haven't played with the camera much, but I am happy with the pics. I am one who doesn't like to fiddle with settings too much. And I care more about getting the pic then making the pic perfect.
The screen to me a bit more vivid then the 900. I think it's to early to tell if the screen is scratch prone. Not sure if Dolby is on by default, but the sound is much improved over the 900 IMO. The 820 recognized my 32GB card and saw and played my mp3s flawlessly. Call quality is good. Slightly lower volume, but the sound is cleaner IMO. WIFi has been connecting flawlessly, and reception is really good typical Nokia. :)