I just received my 4.04 OTA (in China using a Hong Kong sourced 9023) and can confirm battery life is better on 4.04 vs 4.03. As with PvtJoker's findings, Android OS is using less juice at 14% vs 30% with 4.03. I don't use the live wallpaper so screen usage is similar at about 30%.
With regards battery time so far today I'm at 25% after 14hours 39s. Yesterday on 4.03 I was at less than 10% for the same time. Biggest improvement for battery time when first grappling with ICS 4.03 was setting 'keep Wi-Fi on during sleep' to 'Never' in the Advanced WiFi settings.
My CPU usage is still always up at 99% and flat chat at 1GHz so no change from 4.03. It was always pretty high on 2.3.6 as well but given the fact that I'm the only person I know running ICS overall I'm happy.
btw thanks to all who have posted and helped so far - this is a very useful thread.
Just had to pick my wife's iPhone up to take a call (sorry to mention that device here) and iOS looks archaic next to ICS!