I'm writing on the Surface Pro 2 256GB which arrived yesterday. After a full initial charge I detached the power cable and installed Office, Visual Studio and other things, and still was able to get around 6 hours when reaching the 10% battery mark. I'm impressed.
So battery life is not a serious argument anymore, just the form factor if you're able to work on it. The type cover didn't arrive yet, so I'm writing on the screen keyboard and surprisingly it doesn't slow me down that much 😉
Just try them out in the shop, no idea when the Nokia comes out though.