Basically the Surface 2 uses the same kind of processor as you find in cell phones – an ARM chip. These are processors that have been designed to use less power and hence longer battery life. For those of you with a technical bent, you can read more about ARM here (http://en.wikipedia.org/wiki/ARM_architecture).
In practice in means I can use my Surface 2 for a whole day without charging it. If I use it intermittently, I can go several days without recharging!
It has a downside though. You need programs specifically developed for the ARM processor and many of the programs I use depend on Intel processors so won’t run on the Surface 2. But as Microsoft has included the Office suite in the Surface 2, that covers a lot of my needs. And there are apps for most of the other things I do.