I am still learning about my smart phone and I've had it for 2 years!
I like to have my "local" chain grocery store app. It's a 70 mile trip to buy groceries for me and since we no longer get a newspaper with flyers, that too is done online, I can check the sale items in advance. It's the same with JoAnn's.
I also like WhatsApp. It's free messaging, photo sharing etc. As long as I have a WiFi signal, it's good. I have some international friends and phone calls don't always work too well, but with WhatsApp we can have a real time chat if the time zone difference isn't an issue or read the message at our convienece.
For those who have trouble getting a signal in the house, in our case it was because we have a metal roof. Use to have to walk half way out the driveway to get a signal. But they recently put a new tower up closer to us and now I can get calls inside.