We've had ours for almost 4 weeks now. Battery life is, with average to heavy use (lots of Youtube, web browsing, and, goodness knows, Angry Birds) about 10 hours, ~ 10%/hour loss consistantly.
I do have some cautionary preventative actions, though, learned from my having a Pre*:
1. Knocked screen brightness down to 10% or less. HUGE savings in power - that's a large screen to drive. The cool thing is that the screen is still excellent to read, and the brightness difference is unnoticiable.
2. Govnah and Uberkernal is installed, with the 1.5 ghz setting. Only one cpu is overclocked/reduced in this kernal, which is probably not as battery efficient as both of them, but, still good power/performance management.
3. The 3.02 patch is installed.
We do keep it on the TouchStone almost all the time, to keep it charged and usable when and if needed for long periods of time - this, and this alone, is probably the single reason that the TP stands out as a usable piece of hardware above the other tablets. It's so easy to use and still charge, just like my Pre+ on the various TS chargers I have to use it the same way.
It's great to KNOW that you are picking up the device fully charged when you need it, even though you have been using it all day (on the TouchStone charger).
I think most people would fall in love with the TS for either device (pad of smartphone), once they try it - it doesnt extend battery life, but, it assures that you can rely on the device longer when needed, by using it.