Umm, I honestly have no idea. The battery monitor's estimates are horribly inconsistent, and I haven't used it unplugged for long-enough stretches to drain the battery completely. So, at least for me, we can call it "enough".
I have used it for over 4 hrs of active use interspersed with sleep periods (e.g. with the lid closed) without running out. I plug it in whenever I can, which means it gets a little charged whenever I'm at home, at work or at the library (but not in lecture). My schedule means I rarely need to use it for more than three hours without being able to plug in at some point.
Since it doesn't use the switchable graphics cards that are popular in other laptops, this is not an issue. Unfortunately, I think it still does better on Windows.
That said, if it isn't enough, you can always get an extra sheet battery you could attach to the bottom of the laptop--it's pretty neat.
A bit out of topic, but how good does it fare when upgrading windows?
I had a few friends who got stuck on a specific version of windows for driver problems. How future proof would the Sonys be?
Umm, I really, really have no idea (wow, I'm being a useful resource here!)--the first thing I did when I got it home was install Linux, completely overwriting even the backup partition (I had to do that in switching to software raid, I think).
So I've had this laptop for maybe two months (enough time to install the Windows 8 developer preview, granted) and run Linux exclusively. I really can't answer your question.
What I can say, though, is that while Linux tends to have more driver problems than Windows initially, they tend to be much simpler to solve. So if you can't upgrade from Windows, just switch to Linux ;) For every sleepless night I've spent looking for Linux drivers I spent two looking for Windows ones a couple years prior.
