The problem is driver related. If you check the "Get Windows 10" app, it states that the device (Surface Pro 2 ), is not Windows 10 ready yet, and that Microsoft is working with its partners to make that happen. What it means is that drivers aren't Windows 10 ready.
The biggest problem is that most manufactures decided to work on their Windows 10 drivers at the very last minute, sadly. And not during the public beta release of the OS. Maybe they expected that Windows 10 will be released in October like previous version of Windows, and thought they had more time, but regardless, this is the issue. Manufactures are working on their drivers. They first scrambled something to get SOMETHING out the door, but you can see Nvidia, Intel, AMD, Marvel, etc. not releasing new drivers now, it's been fairly quiet. Probably now working on proper support, full featured. Intel for example, their graphics drivers don't support their graphics solution to go under power saving properly right now, causing people who upgrade to Windows 10 have reduce battery life.
So we just have to wait.