I do. I chose the surface pro mainly because of that capability. I used to take notes/annotate my pdfs in classes in my HP TX2000 but now the battery dies quickly, wifi is broken, fan is noisy and it is a little bit slow for new software. So I opted to move to the surface pro. I also needed something that can handle software such as matlab, and such so I needed the power of surface pro (as compared to some hardware that runs on the atom chip)
The experience is very similar hardware wise, but much better software wise. The hardware pen still needs calibration once in a while which I don't like. I am using the Zagg Shield as a screen protector so It feels a little bit different (but you get used to it). I didn't use a screen protector on the HP TX2000 so it felt smoother but by the end, it was riddled with scratches from the pen. Since I am using it everyday, I don't want to be held by the fact that I want to make sure it is ok. I don't mind abusing the hardware and get the most of it in the process.
In terms of software, I like the combination of using touch to navigate and pen to note. The softwares I use for this are: PDF Annotator (
http://www.ograhl.com/en/pdfannotator )Annotate, Edit and Comment PDF Files. Open any PDF file, add annotations and save all back to PDF in one single step. For desktop computers and Tablet PCs, and one note. I really like PDF Annotator and have been using it for years now. One Note MX is cool and fast but I would like more features, hopefully they are implementing the whole one note to that. One Note (desktop version) is still great and better than before.
In terms of time saving, don't see much time saving while writing the notes. However, I see the benefit after that: everything is organized in digital format which makes them portable, paper and ink saving (that is a lot for me since I am attending classes), using digital books, and the fact that the notes themselves are organized in terms of pen colors and such. I just got tired of moving from one place to another and carry boxes of books and notebooks when i move.