I've used it. I managed to get by OK, although I don't love C/C++ the way I used to (and mind you, one of the earliest C++ development systems for PC systems was my product!).
In actual fact, I don't presently have the CDE installed and haven't for some time, since I do stuff in C so rarely these days it's not worth my installing and maintaining it. Easier for me to just edit in Emacs.
Customer surveys are for companies who didn't pay proper attention to begin with.