I've finally bought myself a surface pro and hopefully I can give back feedback on what works and what does not work when comparing mouse input to touch and stylus.
Touch
Selecting: pakset icons are generally far too small for touch accuracy on a 10.6" 1920x1080 screen and would need to be twice as large to be usable. Menu icons are out of the question.
Map navigation: difficult due to scrolling relying on r-click drag or arrow keys. Could use border scroll.
Drag scrolling: possible, but severely clunky
Building: possible, but can be tedious if no keyboard is available for ctrl key.
Zoom in/out: Works great with pinching gesture.
Stylus
Selecting: Icons are only slightly too small. A slight increase, say 1.5x would make up for imperfect precision.
The rest is mostly the same as touch, except there's no way to zoom in/out with only a stylus. Although, I don't think you'd get a stylus without touch input, so it should be a moot point.
For some reason, text is slightly fuzzy, like it has poorly done AA at the edges.
I'd be more than happy to give feedback on anything I may have missed.