Battery is not so last longer compare to ics but few users admitted that they are getting good battery then ics . What all i can say is worth to update to jellybean and its really very smooth and fast then ics .
Do not worry about batter beacuse there is really many tweaks and mods available to make battery longer . So go ahead and flash.
I think I will wait a while because my phone still has some months of services in case of problems. The idea is that I'm not interested in root and sh*t. I'm sick of root and custom-room from the time of using my deceased Defy+.