I was able to download pdfs of music and play some songs off of that. I found that the screen size made it difficult to read a full piano score, however it was possible to read chord charts. I was not able to test this feature, but a friend of mine wound up scanning his music for choir and reading off of that so that he did not have to worry about turning pages or finding the correct page/book. This was very effective for him and I hope to do the same next semester.
I also wanted to expand a bit on my experience with the Surface Pro as a musician. While I am not a composition major, I do have to compose for various school projects. As a test for the Surface, I downloaded a free trial of Finale, the primary music notation program we use on campus, and proceeded to engrave the first page of a Mozart sonata. I tried various methods of entry (touch, stylus, mouse, and USB piano keyboard) and determined that the best way to enter music into the Surface was via a USB piano keyboard and a mouse. Entry was rather slow without a number pad, and the size of a screen only makes it realistic to enter music for 1-3 instruments, but the software worked and proved that the surface can be used as an effective idea capture tool. (Note, I only used the free Finale Software and did not install the Garritan Sound Bank.) It would be interesting to see a Finale App for a tablet so that I could split my screen and have on half be a piano keyboard for entry and the other half be the Finale software.