To preface this post, I have always had Apple products and currently own an iPhone, iPad and MacBook Pro. I have also spent about 4 hours on the phone with Apple support staff and they recommended I make a post on the Apple Support Forums.
Basically, this is a warning that when you backup your iPad or iPhone, Apple only backups contacts, notes, photos, calendars, and mail.
According to the third representative I spoke to, Apple does not, I repeat DOES NOT, actually back up music and playlists in your iTunes on your devices or backup the apps you have on them.
I had to get my iPad replaced because the smart cover was corroding and I did a full backup before I brought my iPad in to the Apple store. When I tried to restore from backup, everything but my iTunes libraries and my apps reappeared. For most, the iTunes wouldn't matter, but I was using a newish computer and had not yet organized my music library, although I had transferred all the songs back from an external drive. The apps are always a pain, since you have to manually download all of the ones you want after going to your purchases in the iTunes store.
However, a helpful thing I did learn, despite the fact that all my music from my iPad was gone, was that you can restore old playlists by quitting iTunes and going to Finder > Home > Music > iTunes and selecting iTunes Music Library.xml and dragging it to the desktop. Then you open iTunes and click File > Library > Import Playlist and select iTunes Music Library.xml from your desktop.
Anyway, this is one of the first times I have been thoroughly fed up with Apple: if their policy is to not back up music or apps when a user clicks backup, then they need to make it clear. Before I restored from backup, those files appeared in my iTunes as if they existed, although according to my Apple representative, they never did.
