here's the demo they showed on the keynote, not as spectacular but it compares the s3 and 920
http://youtu.be/6HSbhyaH0vw

the still with the night shot and light flares of the girl with moving traffic are NOT the 920, because flares require smaller aperture, this one
Source:http://www.gsmarena.com/nokia_lumia_...-news-4769.php

but the girl in the park i believe are actual pics of the 920, this one

however here's a demo of the 920, s3, and 4s
http://www.youtube.com/watch?v=AYYr1cG8hEY
NOTE:flash with the 920 was a focusing light not a flash.
source: video itself.

but with anything announce i reserve final judgment till the final product that i can see for myself, especially the ips display. i love amoled and "always on" clock and notifications

till then still wanna look at nexus device and gonna use my n900

cheers!