Yes, iOS 7, 8, and 9 are supported, and the new iPhones and iPads are supported.
If you plan to upgrade or replace your existing device, we strongly recommend that you back it up beforehand. Failure to do so could result in the permanent loss of your journal. After upgrading your device or replacing it with a new device, restore from the backup you created.
After upgrading, you may experience a temporary issue due to low memory or iCloud connectivity. Find the FAQ entry that most closely matches the symptom you are having, and follow the instructions to resolve the issue, or contact us for further assistance.