What makes a good iOS app?

We were asked this question on our Udacity iOS Nanodegree class.

What makes a "good" iOS app?

To say that this is subjective is an understatement. I think there can really no definitive answer(s) to this question. "Beauty is in the eyes of the beholder" so to speak. '

Anyway, I'll put my 2 cents in and tell you what I think makes a good app. I have 3 things I look for to decide whether an app is good enough to keep. Here they are.

It must be simple. 

In order for an app to be good, it must be simple to use. It should be easy to learn and it should not confuse people. One example of this is Google Photos. When you open up the app, you get your photos right away for viewing. You then have only a few options so that things are not overloaded. Each option is also pretty straightforward. There is no guessing as to what something does. 

It must be useful.

This may sound simplistic and obvious but an app is no good if there is no good use for it. I use my mail app everyday because I need to check my mail. I use the Music app because I listen to music. I use Maps because I want to be able to go where I need to go. I use Facebook because I want to connect with Friends and Family. Essentially, what I am saying is that a good app needs to serve a purpose in our lives. 

It must be well designed.

Usefulness and simplicity would not be enough. An app becomes great when it is well designed both functionally and aesthetically. The layout, the color scheme, the icons, and all of the other elements would need to be well thought out in order to provide an overall pleasant experience for users. 

So, there you have it. There's my 3 criteria for what makes an app good. Let me know what your criteria are. I would love to here your opinion.