I have depended on cygwin for years. For years my main development platform has been cygwin emacs, writing Perl and C++ and Python to be uploaded to various Linux machines and run.
I just upgraded to CYGWIN_NT-6.0. Running on Vista.
And I am plagued by instabilities. Emacs running out of resources, vfork failures.
And everything is much slower than the older version of Cygwin on same Vista machine. E.g. I may no longer be able to run git - too slow.