Not Exactly actually. ICS requires more power to perform, so the battery consummations will be higher as well.
And it varies for different device. ARC S has some battery drops after the ICS update. On the other hand my Xperia Mini pro and Xperia S got slight battery back up after the ICS update.
Your phone can loose 10% in 3.5 hours easily if you keep the data plan or WiFi or GPS on. So in ICS make sure you do not keep those on once the use is done.
Also disable some apps that you do use occasionally by going to settings-Applications-All applications.
Uninstall the Anti-virus if you have any, Android doesn't need anti-virus as long as you download apps from the Google play.
Do a factory reset if you haven't already. Take out your SIM CARD and SD card.
Power On the device.
Open Dial Pad and type following- *#*#7378423#*#*
You will get a menu-
Select Customization settings-reset customization
This will reset all the settings, data of your device to stock condition. Device will restart and first restart may take some time.
Usually it is recommended to do a factory reset before the ICS update.
***Remember Reset will remove all the data stored in your phone. Contacts, Msgs etc. So keep a backup first. However your SD card data won't be affected.***
Once done resetting, download the following software, Install it to your PC and follow the onscreen instructions. It will re install the ICS to your device one more time and it is recommended to have SIM/SD card in the device while preparing.
Update service - Sony Smartphones (UK)
And also after repairing, try to use a fresh memory card, by this i mean a formatted memory card. [Keep back up]
These will not bring any drastic changes but you can see some differences.