I tried D in the past but got demotivated so never learned it fully. From the little that I used it it's a better language than C++: the well designed library, the built in strings, arrays and maps, all make it a very elegant and practical language... which unlike C++ is actually high level. Then again for C++ weenies anything above machine code is "high level", even assembler.
Anyway back to D, unfortunately they refuse to standardize it by way of ISO/IEC, because who needs standardization amirite? "Other languages do just fine without standardization." Yeah because they're backed by big corporations, big money, maybe even a government.
Ultimately, the philosophical problem of D is that in order to fully appreciate it you need to be an above-average C++ programmer in the first place. But if you already are, why the fuck would you leave standard C++ for what is basically an unproven language? Methinks toying around with D as if it was a hobby project (which it is) should end immediately, and the language standard should freeze its features in, let's say, ISO/IEC D20, in time to poop on C++20's party. But that's not going to happen because suddenly winning over C++ programmer's isn't the goal anymore... the goal now is having fun or whatever.