Reed College ran an iPad Pilot Program, and found iPads much more flexible than Amazon Kindles in the educational environment. Their (limited) study does not deny the potential for other tablets (Android-based), but does focus on the iPad.
The summary mentions the difficulty of downloading, organizing, editing/annotating, and sharing PDF files. Not surprisingly, many people do not consider sheet music PDF readers, such as UnrealBook and ForScore, which would have solved many of their problems. I’ve recommended these apps to a number of people with iPads, and it is amazing how flexible these programs are beyond their use in music.
Additionally, the summary mentioned the sad lack of a physical keyboard. It’s too bad nobody makes a small, portable keyboard that could be used with the iPad (Note: this is sarcasm. Not including Apple’s own iPad keyboard and bluetooth keyboards, nearly any bluetooth keyboard will link with the iPad, normal keyboards can be used with the USB dongle, and many new cases are coming out with keyboards included, such as the new clam shell case).
Here is the Reed College iPad Report, in the event you would like to read it.