A must read inside look at Apple by Lance Ulanoff on Mashable.
And this section below is a good reminder of the simple principle that has been key to Apple's success - the ability to design the whole thing (something that Microsoft seems to be coming around to as of late):
"From the beginning, the Mac has been about Apple taking responsibility for the whole thing: hardware, software, how applications can work and, increasingly, Internet services. But that means something different today than it did 20 years ago," Schiller said.
"Today, those teams are not only integrated and designing something together, they’re actually thinking of features that could only exist because of that integration and solving problems that could only be solved because of that unique advantage."
A simple principle. Very hard to pull off. Think of the integration used for Apple Pay alone (Apple "A" series SoCs, Touch ID...).