When I bought my S3, I took my SP3 to the MS store and I compared the stylus feel on the S3 and the SP3. There was a difference, with the S3 being more comfortable or responsive. I thought I was imagining things so I asked a couple of the sales people to try it and they were surprised, too, but they felt the same thing. That's just trying one of each so it's not a good test, but I did detect a difference.
I haven't tried handwriting recognition with mine. I connect it to a projector and use it like a whiteboard when I answer my students' questions. I applied a nonglare screen protector that makes writing feel very much like writing on paper.