Moving to ICS on the Samsung SII has been underwhelming for the most part - partly driven by the fact that the UI has been kept relatively stale by Samsung, and made worse by the fact that ICS while powerful, has more than a few hiccups during operation.
But there is one aspect that ICS is really good with - memory management. ICS comes with a Honeycomb inspired task switcher that also doubles as a task killer. Flicking an application in the task switcher kills it, releasing the memory and plausibly making battery usage better.
Well at least that was the theory, till I tried to put it in practice and presto - it worked! Check out the screenshot showing a run time of a day and eight hours with more than 40% of the juice still to go. Yes, the usage was not as heavy as I normally do with the phone, but still a 32 hour run time was not something I had frankly expected.