What concerns me in particular, is that at least with the KDE 4.0 debacle, there were quite a few "This is BAD... But I can see it being good in a few versions" type comments.... with Gnome 3, can't think I've seen a single positive comment, at best "changes are sorta manageable".

Yup. The problem with KDE 4.0 was that it simply wasn't even close to release quality; it was early alpha at best, with large chunks of functionality either buggy or unimplemented. 4.2.2 was the first version that I could imagine anyone using as their default desktop; I switched somewhere in the 4.3.x sequence.

The problem with GNOME 3 is that the fundamental design decisions are wrong. No amount of bug fixing etc. is going to make it usable.