The iPhone's flash is pretty fast.
My battery life was much worse after upgrading. I then did an OS install with the phone in DFU mode, and then restored settings and synced. Still same battery usage issues. Next I turned off a lot of features, and that seemed to have helped. There are a lot of reports of battery life issues. Maps is getting a lot of heat (I haven't noticed anything "bad", but I've not used it much). Auto brightness doesn't seem to work, or they've changed the way it works.
Currently I'm running some diagnostic software to gather usage battery usage data.
From posts I've read on other forums, various settings changes or even setting up he phone from scratch has resolved the issue.
A Co-worker was having issues with her battery life and wasn't getting the answers she liked from the Apple store so she e-mailed Tim Cook. He called her at the office the other day to cover the issues and gave her the contact for his tech team if she has any other issues. gotta admit that's pretty good customer service.
"We've been attacked by the intelligent, educated segment of the culture"