A:
I bought a Surface Pro while I was in the USA and have used it as my main computer since, so here is my experience with the battery.
I was using it at the conference to take notes in meetings and show people powerpoints with it in my hands. Using it like this, so not presenting or using Excel all the time, it lasted me the day. However, when I was flying back I was able to get about 6 1/2 hours constant e-mail and other non-intensive app usage out of it and it still had a bit of juice left in the box.
I've also used it as a games machine, where it was going full tilt and I believe it would have lasted about 3-4 hours doing this.
I hope this helps.
David