Frankly, I got the same experience with you after upgrading to ICS from GB.
I was upset when my phone cant last 10 hrs not even a day after a full charge. I tried some apps like Watchdog Lite or Juice defender but it doesnt help either. After reading some tips in this forum, Ive learn something. I just made a factory reset on the phone and things had change on the battery life since then.
After a factory reset, I fully drain the phone until theres no more power when u turn on. After reaching 100% charge, take out the battery and put back after a minute or two then power on again. Do this once every or 2weeks. It takes many times or cycles for the battery to learn itself to live longer.
Also made changes on habits.
I dont use facebook android app unless u need to upload photos, I use FBM app(free) less than 1MB compared. After using the web, always turn off the wifi and data, look on active applications that is running and stop it once youre done. Dont use that CLEAR RAM(built in processes) thats a drainer too. Turn off autosync if u dont need it like emails, msgs. Set ur display brightness very low like 10% since its very clear at dark. etc. To sum it all, my battery can last 2 days on a full charge, its on everyday using wifi and data and off at nyt. big change for me.