Develop a single application, that relies on the same API set and runs across,
PC, Phone, XBOX, Micro... aka Desktop, Mobile, TV, Everything Else...
I would say that's pretty impressive if they pull it off, considering how many customers and scenarios that will span.
[1] http://blogs.windows.com/buildingapps/2014/09/30/universal-w...
Sure, but unification was part of the big pitch for Windows 8. Of course, it wasn't quite what they did, but the fact that it was the pitch for the last major version makes the "this time we really mean it" repetition of the pitch for Windows 10 less overwhelming. Fool me once...
The fact that they're consolidating the console, desktop, and tablet/phone OSs is the impressive accomplishment, not the phone/tablet consolidation.
As for consoles, a few years ago, consoles were a whole different beast from what they are now, so it wouldn't have made much sense to have the OS the same.
Apple understands that different devices need different UIs but can share code and core APIs.
Microsoft thinks that different devices should have the same UI but hasn't previously managed to share code and APIs.