Their mistreatment, lack of support and quality assurance of the mobile side of the platform has been dismal. It's very weird, obviously they can do hardware, they have the ecosystem to back them up and the API teams have been doing some great stuff when it comes to w10, yet they've seemed to given up on mobile.
I must say I don't understand it, how can such a big player as Microsoft abandon such a strategic area of their ecosystem? I understand that it's hard to be a profitable in the harsh reality of consumer electronics and that the money is in business... but yet, if you're not in mobile you're leaving a gaping hole in your ecosystem that leaves the other parts vulnerable. I don't understand why they don't simple pour resources into mobile with the same enthusiasm as tablets/laptops and gaming.
Something must be off with the leadership or I'm missing something