|The only interesting things are optional and therefore won't be supported by anything ever anyway.|
I can't imagine any major vendor (Intel, IBM, HP, etc) not supporting threads or atomics, especially since some compilers already ship stdatomic.h and threads.h -- Pelles, for example, has threads, and Clang has the atomics. Complex numbers and VLAs have been there forever already, and that doesn't leave much stuff that's optional.
I fell in love with VLA's, variadic macros and compound literals.
Compound literals are really nice, I agree (and named initializers too.. and of course the ability to declare variables where you need them)
|I have no interest in C11, because I don't see the improvement.|
Granted it's not as insanely huge as C++11, but the little bits are helpful. Static asserts (which my XLC already supports), alignof/alignas/aligned_alloc, etc. The generics have potential, too.
I think the most important core language bits are thread-aware memory model, and locale-independent Unicode support, and those aren't optional.