I was worried about the battery life too, but today it's proved to hold VERY well. I got up from a nap around 4 and now it's 10:39 PM...so ~6 hours...few youtube videos, some web browsing, updated/installed 12 apps, 3-4 phone calls, 20'ish texts, took a couple of 30 second videos of my daughter, a couple of pictures....and I'm still at 80% battery. (says 2 days 17 hours remaining but i'm sure that's inaccurate)
update: 1:40 AM ~ 72% battery remaining with additional texting and moderate web browsing. (says 1 days 23 hours remaining, but once when i looked at it earlier it only said 17 hours...not sure the reason for the inaccuracy, but i think it will become more accurate with time)
That's VERY good...even compared to my old Samsung Focus - which I thought had one of the best battery lives of any phone I've ever used. Props on the 920's battery life.
P.S. I read an HTC 8x vs Lumia 920 review walking into the AT&T store yesterday that said the 920 won on battery life...which was my final deciding factor on going with it.