hahaha... ok so here's something interesting.
My battery life on 1.5 was awesome! I tweaked the hell out of it and got consistent 15+ hours if needed with regular use.
On 2.1, this morning I noticed that I used 20% battery in one hour (stock battery) while browsing web and using market, installed 1 app. Then I put phone down and didn't touch it except to check battery every hour. It took almost 4 hours to burn another 20%, which surprised me.
So... it would seem, if the phone isn't doing anything, it tends to handle down time better with respect to conserving battery power. While in use, well now, that's another story.
I have since tweaked a few settings mentioned here and elsewhere.
Two other things to note:
1. Interestingly, the web browser reset my Homepage back to Sprint's... ??? Lol, anyone else experience this after changing Homepage?
2. The Camera is LAGGY as hell now in 2.1, couldn't get a picture last night that wasn't blurry. I tried a multitude of setting changes to get a better response, i.e., ISO, Quality, Size, etc., with no luck.
Other than that, I have no other lag issues.
Happy Trails!
P.S. - if you want to see some really cool information on the battery, use the service menu... First, please, don't change ANYTHING that you do NOT know what you are doing as ONLY YOU WOULD BE RESPONSIBLE for any problems thereafter.
Goto your phone dialer and type in...
*#*#4636#*#*
wait a few seconds for menu to show up.
then check out battery history and usage statistics is good too.
Enjoy!