I used CDE when Motif was still state-of-the-art in X, and it was by far the best unix desktop environment I had used up to that point.
I've used every other wm under the sun and I end up spending more time configuring my damn window manager more than getting work done. So much lost productivity vs just not using them to begin with.
CDE still does one thing that no other wm seems to be able to do: completely consistent behavior everywhere