With iPads and certain published folio's coming of age, it's time to renew your iPad. First surprise: you need to download all folio's again. Second surprise: some publishers tend to withdraw published folio's (for which I might have paid), so there's no way to retrieve them anymore !
The same happens when you have "archived" a folio (I never trust any term like that from Adobe no more) or needed to restore your iPad for some reason. The multi-folio apps are there, but some folio's don't appear back in the library.
This is definitely a "rip-off" !