1st thing to do is get cpu spy free from google play and better battery stats (small fee from google play or a free d/l from xda forum). They may well reveal that there is some process preventing deep sleep. If so, check xda for solutions/workarounds.

Specifically there is a bug which is affecting many notes on ICS whereby if you disconnect the charger without first turning on the screen and unlocking, then the CPU gets stuck at 200Mhz due to a wait_lock.

More of a long shot but also worth checking your 3G and wifi signal strength relative to how it was in same places on GB - lots of reports of stock ICS giving poor reception (hence faster battery drain as more power gets drawn by the radio). You can flash alternative modems in place of the default to address 3G issues, and/or flash an alternative kernel to address wifi issues. Best to do some reading on XDA forum first though if you suspect this may be the case.