I don't think it's defective. It's a bug for sure, but I have completed some pretty precise work on the surface book. I guess you just have to be a little quicker with your strokes. See attachment
All 4 of my students that have Surface Books don't like it. It depends on you're working style...if you tend to draw fast and undo very often it might be ok. I prefer to draw with a slow controlled line for small details. FYI my students use it for cleanup linework for manga as well.
Also, you're drawing curved lines here. Try drawing straight lines at an angle of 45 degress slowly as you would need for drawing something architectural...you WILL get a wiggly line. It is a defect that is widely known on different forums and apparently has been around for a while. Might never be fixed as it is likely a defect with the N-Trig technology.
Here's another place where people are complaining:
Surface Pro 3 Wavy diagonal lines when inking
Finally, I noticed that you are using Manga Studio which offers a brush stabilization feature(though you might not be using it and might not need it if you draw quickly); basically if delays drawing and smooths the line as you draw. What i want is 1:1 clean input from my hand to the drawing surface at any speed at any angle. N-Trig simply CANNOT do this.