About the comment on battery life and 3G/4G connectivity:
Based on my experiences on similar Ultrabook, the battery life drain depends on the tasks you are doing. For simple document and file editing, turn down the brightness a little, turn off wireless you can easily get 8-10 hours of battery life. For video playback, depends on the brightness on screen, you might go for 5-7 hours. For very demanding games, the battery might run out in 3-4 hours. For older games which uses little of 3D such as Baldur's Gate and such, you are getting 5-6 hours. Yes, it cannot be compared to those 10+ hours in Android and Apple tablets, but the games are so much more fun. And it can easily play all video formats unlike the situation with Android and iPad now.
3G/4G does not necessarily requires a USB dongle, a portable hotspot device is small and dirt cheap so just plug the USB dongle into it and get 3G/4G access via WiFi. Or if you already own Android device or iPad, turn them into hotspot.
Such a device can do much more than Android tablet and iPad can do. It is in a different class of devices altogether so you might see people buying both of them. Of course, for some people, Android or iPad is good enough and they have no use for Surface Pro. For a lot of us though, we might just skip over Android and iPad, and get our needs met by this.