The phone is running Android 6.0 with Huawei’s custom EMUI skin.
I’ll start with one thing I absolutely hate about customized versions of Android: bloatware.
This is a bad user experience and something that should be eradicated entirely from Android.

Most of these duplicate apps are completely unnecessary and offer basically no additional functionality.
OEMs should just choose to keep one app and remove the other; it’s not that hard.
I’m not saying that all Android OEMs have to use stock Android.
Skinning for the sake of skinning is bad; evolving the OS through clever, useful additions is good.
The notification pane is very different from stock Android.
The Huawei P9 also has a terrible habit of nagging me with annoying notifications by default.
There are some good features found in the Huawei P9’s software.
At the same time, there are some features I didn’t feel the need to touch at all.
With that said, I’m sure some people will find some of the additional apps useful.
Plus the dedicated apps for a torch, mirror, compass and so forth could be useful at times.