I don't get how UEFI is still "getting the kinks worked out." Hasn't Apple been using it since they converted to Intel? How many years ago was that? How long does it take to "get the kinks worked out?" Or is this more of an issue between Windows / Linux implementations of UEFI support?
Apple makes both the OS and the UEFI implementation for their hardware. If the UEFI implementation caused any trouble for OS X, they could fix it before shipping the hardware. They also use a non-standard EFI implementation (IIRC the EFI partitions are HFS+ rather than FAT; whoever thought it was a good idea for EFI to read the partition table whatsoever should be fired).
The issue with PC hardware is, as it ever was, hardware vendors not following the standard. Much like Apple and OS X, they build some implementation and only fix bugs if they break Windows. So if you want to build a Linux implementation, you have to implement workarounds for all the quirks in different vendors' EFI implementations, and in the meantime you can't install on their hardware.
It's the classical problem of a standard that nobody actually follows. Every UEFI firmware that I have come across has behaved differently.
My current laptop has an UEFI implementation that only boots from a hardcoded path in the EFI partition. You guessed right, the path of the windows 8 bootloader.
The UEFI in my home server overwrites the UEFI boot manager list every time you save & exit the configuration tool.
If I remember correctly, the UEFI implementation of a MBP that my friend and I tried to make dual boot Ubuntu required a blessed HFS boot partition for every OS.
I'm really biased against Intel processors now because of this - I endure my distaste for how horribly documented and black box their parts are, but the fact their firmware for going on 6 generations has no documentation to enable coreboot on these boards drives me to AMD.
Yea, they don't open up all their stuff, but if you dig around you can usually find a board on most chipsets that works with coreboot. That gets my purchase. Plus they are doing good work with the radeonSI mesa driver, even if they still pack binary power firmware with it (I've read a few articles decompiling and inspecting it to know it is mostly just init command code to start the hardware).
