For some reason whenever my battery gets to ~15% it does a jump right down to 5%. Not sure if maybe the battery % widget I use is wrong or not, but most of the time I get no warning at 15% or 10%. After that it seems to drain pretty quickly. The battery tends to drain very quickly in general, after the JB update. My 15 minute bike ride to work used to only show the battery drop 1% (not using apps, screen off, etc...) and now it drops 5-6%. I'm not even using it! And to make it worse I can't even put it in sleep mode to save battery when not in use, but I'm ok with leaving it on now that I have my Pebble Smartwatch to use with it. Still kind of mad the battery dies very quickly.
Secondly. I cannot root. The Razr-Blade root utility goes all the way through. Says the process is done, but the phone is not rooted. it doesn't hang up on any steps, but it says some files failed to change or add. I had root on ICS and updated to JB through the official update without unrooting (didn't know to unroot). Now I cannot root to do some root things I used to that always helped save battery.