My Battery life is much improved. I charge my phone over night most nights and head out for the day. Before 2.2 I had to charge my phone at the office or else it would die before I got home at night. Yesterday I went for 15+ hours without a charge and finally plugged the phone in. Right now I have had the phone unplugged for almost 9 hours and still have 65% of the battery left. I have a go worker that has the EVO and has also noticed a huge performance gain with froyo.
As for App killers and apps continue to run even after you kill them, this has been posted on a lot of the forums as that froyo manages apps in a new way an most task killers do not fully kill the apps. On the other had there is a white paper out from Google about how you should not have to kill apps and you should let the apps run naturally and froyo will kill them if needed.
Over all I am very impressed how froyo has improved the phone and battery life. Before the update I was looking at getting a larger battery, and now I don't see the need especially being I am getting over 15+ hours on the regular battery. I do get constant updates and streaming of news, weather, facebook and so on. I do not use it as an MP3 player through out the day, but I use the phone as a phone and web surfing device.
