The Verge:
All the power of the Surface Pro came at a cost in battery life nine months ago, but I'm happy to report that Microsoft's promise of a 75 percent improvement for the Pro 2 is genuine. The Surface Pro 2 lasted 7 hours, 33 minutes on the Verge Battery Test using Chrome, which cycles through a series of websites and high-res images with screen brightness set to 65 percent. That's nearly double the Surface Pro score, which lasted for 3 hours, 59 minutes. It's the same package and screen, but it's clear that Intel's Haswell chip is helping to improve battery life here. While it's not the 10 hours you might expect from a tablet, given the compromise for laptop-style power it's definitely acceptable.
Review is pulled due to embargo but should be up soon.