Agreed, I lost 50% battery life with the update. No new apps added from ICS to JB nor did I change my phone usage habits. I went from 48 hours down to 23-24 plus:
A couple apps force close now(games mostly)
Runs noticeably slower when trying to open apps
Surfing the web is faster on a 1995 laptop with a 56k modem than my Razr on 4G(I can literally search for something, get out my other new laptop, turn it on from a cold start, connect and then research my query before my phone has even loaded the page fully)
Wifi doesn't work anymore
And finally(AND THIS IS REALLY RANDOM) JB deleted lyrics from songs. The song information itself is still there, hell even the background music plays when I click on it, but the lyrics and actual singing/rapping/whatever is just gone. I have to re-download about 120 songs because there are no lyrics anymore, just instrumental tracks.
Had I known all this, I never would've updated(Took me weeks to figure out how to update after I deleted some important APKs, turns out my phone was trying to save itself from a downgrade). The battery life itself is a huge downer, the other things I could've gotten over but a loss of 50% of my battery is impossible to forgive.