Remember this: http://www.theguardian.com/technology/2011/apr/20/iphone-tra... in which the location history of users was tracked and offloaded to the user's PC when synched? I get that the "problem" was allegedly fixed, but there's absolutely zero reason to trust anything Apple says here. The potential of getting hit with National Security Letters with built in gag orders invalidates any conception of trust between users and groups that handle their data.

There could also be hardware or software backdoors/exploits that Apple has no clue about-- I would say almost certainly, given how inventive the NSA has been with both of those angles.