I've just switched from Galaxy S4 to Huawei P9.
The most annoying thing I've noticed so far is the background color of incoming calls.
At work I have the phone in silent mode. When the phone is inactive, the screen is black (naturally). When I get an incoming call, the background is still black and the information on the screen is minimalistic.
It's therefore very hard to notice the incoming call when my focus is on my computer screen.
Is there any way of changing this without hacking the Android OS?