I'm an Apple user since 2006 ... here"s some points.
The Intel Switch and the use of a BSD based mach kernel has saved Apple.
If you look at the reliable part of OSX, not Sandboxing, Document Versions and iCloud,
you'll note that everything that is really the base of all of this is still BSD/Unix based.
I would like to see Apple innovating not only "on top" of this layer, but really work on
Virtualisation, Memory Management, a real File System and so forth.
BUT, I do believe Apple is not capable to do these changes.
Aside from Chris Lattner (sp?) who is working on Swift and LLVM related projects,
Apple has not created a new great low/level approach to something.
Most of you might not really know what I'm trying to express here, I'm sorry.
Modern CPU and GPU hardware has so many exciting features that are currently not used by OSX at all.
And I explicitly do not talk about Final Cut or some other Pro Software.
I mean a new concept for the really low level stuff.
If you take time and read about the Mach Kernel and look at the low-level API's, you'll quickly realise that
Apple has just been able to keep up supporting new hardware components but there's next to no innovation.
Examples just from the top of my head:
A new virtual memory manager with virtualisation build into the OS
A new filesystem (versioning, compression, replication), no CoreStorage is just a block device abstraction
A new NETWORK filesystem, not SMB or AFP
A better GPU abstraction layer that supports stuff like CUDA (sth like DirectX)
A network enabled centralised Spotlight Service for your LAN, shareable on iCloud and ties in to the network filessytem
A better TimeMaschine implementation that's not just hard links on a sparse bundle
I could go on and on ...
I really do NOT care if the appearance of a button changes.