IPad mini, plenty of storage room, not jailbroken, good network contact. Upgraded to 0.15.0 after never having any problems of any sort with MCPE in previous versions. After upgrade, Mojang loads, main screen loads. Skins, Xbox login, options, etc are all ok. All old worlds from previous versions are gone, and so clicked create (creative). Building terrain screen, gets about half way then crashes out to iOS home screen. When trying again the failed world is now on the menu with a 0.0kb size. Deleted to old worlds, tried again, same results. Have tried with Xbox live logged in and not logged in, no change.
This is more than a minor bug. It's a complete show stopper for the program. Take a look at the comments on the App store!