I just updated to iOS 9 on my iPhone 6 Plus. Here are my initial notes:
New font looks great. Very easy to read and matches the bigger screen of the iPhone 6 Plus. The update looks cleaner and is easier to read. Not a drastic change, but feels fresh.
The keyboard has upper and lower case keys. You can now see when you have activated the shift key. Excellent!
Passbook is now Wallet.
News is turned on by default. I’ll try this out a little and see what it does.
You can add the iCloud drive app to your home screen.
New section for the Battery under settings. You can switch on low power mode to temporarily reduce power consumption.
You can search the settings instead of just scrolling through. This is a handy update.
There are some bugs with how the apps appear. There are some logos that don’t appear and the text overlaps the app logo in some of the sub menus.
Wallet & Apple Pay now have their own menu.
Find Friends is now a default app on your home screen. You can have the app notify you when your “friends” arrive at a certain location.
The Mail app looks cleaner and is more responsive.
Using Siri to respond and the sound wave has changed. In my limited tests, it seems more responsive and accurate. Digital dictation keeps getting better.
Apple Watch Update (not yet)