I already have an incredible, so I when I heard the TB had bad (worse?) battery life I went ahead and bought the extended battery at the same time because my Incredible can't go half a day without needing a charge with the regular battery. I consider myself a medium to heavy user, so being able to go a full day with some battery life left is what I would consider good battery performance.
Just for kicks though I wanted to see how much life I could get with the regular TB battery. First day I picked it up at the store in the morning and played with it while it fully charged at work. Then basically didn't leave it off the rest of the day and it had plenty of juice left when I went to bed, but I still charged again it anyway. The next day I left on wifi - which I use at work and home, and I tried to drain the battery the whole day (GPS, streamed music and video, internet all day) but gave up past midnight at more than 30%. I though it may be because of the wifi, so I tried using only 4g all the next day and it lasted all day just fine using it as much as I pleased.
It's been a few days and I don't feel like I need the extended battery, I haven't opened the box yet so I may just take it back. Supposedly, battery life should get better after a few more cycles which would be even nicer. The TB is running just fine, and 4g is ridiculous. I'm not crippling anything, and I have a lot of apps installed. Maybe I just got one of the good batteries?
I've been hearing so much negative comments about the battery, just wanted to see how many other people are satisfied with the battery life.