This is a word of warning, I have about 2,000 users with one of my apps, about 5-6 of them have lost all their data after the upgrade to IOS7, the database that the app uses has gone, it is not in the icloud or itunes backups (or it does not restore from the backups of them), the only reliable way to upgrade is to use itunes to take a physical copy of the database before upgrading and then to put it back after if there is a problem with the upgrade, I have some seriously pissed off users that have lost significant amounts of data.
I have told all the rest of the users to not upgrade until I can try to fully understand what is going wrong.
atb
alex