I bought D4 on the first day it was available, since it was my birthday. My D4 is not rooted, since I, too, am relatively sure that I would screw up the whole thing. That being said, I'm coming off a Droid2 Global, and I am impressed with battery life so far on the D4. I have most things turned as low as possible, including the video screen. I use my phone frequently throughout the day & when I play Angry Birds, I make sure the phone is charging or fully charged. AB will eat battery life like nothing else I've seen. Just sucks it right out.
I had 2 extra batteries for the D2 & would regularly go thru 2 fully charged batteries in a day. For the D4, I bought a couple of external batteries to give me a little charge after a long day, but I rarely have to use them.