The camera is better but you can compare the detailed specifications on gsm arena on the link
Samsung i8910 Omnia HD vs. Nokia N8 - GSMArena.com
Nokia Camera is better, the N8 in comparison isn't much to talk about. As usual nokia could have gone all out but they held back again. If you have an i8910 then its not worth getting an N8, just for the camera & software update to symbian anna & belle.
Skip the N8 I look for something else, Nokia doesn't show confidence with their products, so why would customers. Symbian is dead, Meego killed before N9 launch, nokia places hope for windows phone? How about you?