As I musician I have used thr GoodReader for 2 years. Even though it doesn't have the bells and whistles of the "music PDFs", for the working musicians it beats all music app by a long shot.
Version 4 is even better.
Ver
Display 2 songs in landscape mode. I've had music apps tell me that it's impossible to display 2 pages in landscape mode. They forgot to tell the GoodReader that.
You can type in the pg number into the page icon and it will go to the right page.
Ver 4
In the thumb nail section
You can copy, export, import , rearrange songs,ie make musical set lists. Print, email.
Sterling