Just moved up from a Desire to get the one a couple days ago. I was using a custom rom on the desire (SU's rom) which let me get upwards of 2 days of battery life with medium use.
Just got the one, decided to still keep it stock for now and not root it. The battery life has been much much better than I expected, heres a screenshot of my last charge cycle, I had to take it off the charger before it hit 100, but it still held up to one day of gaming and other abuse. :P
Here it is:
I do have a couple questions though:
How many charge cycles can this battery stand? (is there an estimated amount that can be given?)
Is it still really bad to take the battery below ~15%?