I have been developing Windows software since Windows 3.1 and my first UNIX was Xenix, followed by DG/UX, Aix and many other variants.
Windows is perfectly viable developer OS for C++, Delphi, Tcl/TK, Perl, Python, Java and .NET developers.
Microsoft did a mistake not following up on Windows NT POSIX support, because that is what many care about is POSIX shell utilities and C APIs, the actual kernel is irrelevant.
However now GNU/Windows fixes that problem.