Surface Pro does not include WinTab digitizer drivers, the industry standard tablet API used by Photoshop, Autodesk, Wacom, and virtually everybody else. Instead, Surface Pro uses a new API for pen and touch input which is not supported by existing applications. Without WinTab drivers, apps can't use tilt, pressure, or the eraser, so the stylus just acts like a mouse.
Microsoft is "working with" Photoshop on a solution (iow angrily demanding that Adobe support their broken ****, which they never will because Windows 8 has a lower market share than Linux), but for now the Surface Pro effectively can't be used as an art tablet.
So here's where we are. The Surface Pro (with cover) is more expensive than a Macbook Air, runs one of the most hated operating systems ever designed, has half the battery life, weighs about the same, and you're still lugging around an Intuos either way because Microsoft's NIH syndrome put a bullet in the head of the single redeeming feature of the steaming pile. And the best way they can think of to express the value of their product to the average consumer is to get people to dress up as yuppies and breakdance in a San Francisco hipster recycled warehouse space-style startup incubator. ****in rad.