When using iPad if you don't have Internet connection you cannot search downloaded, offline books - even downloaded Bibles.
It would be really nice, given that books can be downloaded for offline reading, to be able to - perhaps by user choice - have them indexed. Understand that indexing could be problematic to enable for all books (hard to know how many books downloaded) but perhaps just for downloaded Bible(s).
Having book downloaded but not being able to search them is a little frustrating.