Here is a list of functions I used often (just for self-reminder):
Photos and videos
I had tons of photos and many videos recording my trips, the growth of our daughter, some daily information and even my experiment results (Not kidding! I even used one photo as a figure in my publication)! So truely camera is a must-have (who doesn’t have a camera?).
Family sharing of photos, videos, and apps
Family sharing in iOS is great. Because we are far from our parents and friends in China, through photo sharing, they can easily get updates of us. Also, they don’t need to pay again for apps I bought.
iMessage and Facetime
Everything integrated into the OS is better to use.
It’s pretty useful to track routes while using running / cycling apps.
Although it’s not so comfortable to write on a small screen, it’s good for keeping some short notes.
Qianniu (an app for Taobao shop)
Similar to eBay, you always receive messages in time.