My Iphone had pretty good battery life. I never actually measured it but battery life was generally quite good. About a week ago or so I updated my OS to the newer version and this last week I have noticed that day by day my battery life has been getting worse. I pretty much turned off everything and closed all running applications and still within about 2 hours time my Iphone 4 lost about 21% of battery life. I do not have many applications on my Iphone 4 and do not have mail switched on to fetch mail. No Bluetooth,No wifi switched on either I like the new features after the update but the battery life drop is not just on the new Iphone 4S but now on the Iphone 4's as well so I reckon it is something to do with the new OS.