My D1 will die within 6 hours of moderate usage at work. By Moderate, I mean facebook/twitter checks maybe twice an hour each, maybe 20 texts back & forth, some web browsing on my lunch hour, maybe a youtube video or two.
If I can do heavy use with 6 hours+, my basic usage should easily get me through the workday! dancedroid
EDIT: Forgot to mention I also leave my Wi-Fi almost all the time, but I have no access point at work. I know that'll kill the battery some, but in my experience, it wasn't a substantial enough amount to bother with.