Application 1
Sync contacts and calenders between mac, ipad and iphone.
Application 2
Sync files between iCloud enabled apps like goodreader or pages.
Application 3
Sync the music YOU BOUGHT VIA ITUNES between mac, ipad and iphone.
Application 4 (iTunes Match)
Sync the music FROM OTHER SOURCES (e.g. Amazon, real CDs, …) between mac, ipad and iphone.
This service is not freely available. It costs 25,– € per year.
Application 5
Backup the ipad/iphone device in the cloud.
This backup doesn’t include your music files.
Hint: The backup of an ipad/iphone never includes the music files. It doesn’t matter if you backup via itunes or icloud.
Average size of my backup file for the ipad/iphone is ~300 MB.