KWin is progressing fast and it's getting better at a good pace. On the contrary Compiz will always lack integration... I already can see a drop in the use of Compiz. It's still good, but it will lose ground, and will probably die someday as the "once upon a time revolutionary technology XGL".
I agree, I'm using KDE 4.3 and kwin while not over the top, is great and impressive in a elegant way. With the instability of the Compiz project (rants and forks), who knows how long it will continue, for now it will. Its definiately ahead right now though. But for how long?
And what's the problem if even finally dies. The matter is the technology and the desktop way which will offer for the successors to adopt.
I love when a great program dies because that only means that an even greater one is born
Gnome-shell will break something else I consider to be a major possibility in Linux: You will lose the ability to use other desktop-managers with gnome, or if you do, you will lose the Gnome-Panels and everything. That's the bad side to "perfect integration".
What I think is one of the best things in Linux is, that you can always combine everything with everything (only think of the "small" shell programs like cat, tail, grep and all those). However, I feel gnome (and maybe KDE too) are developing into a direction that is too integrated (and it will not only stop you from using compiz the way you did up to now, but also stop you from using ANYTHING else - which means, nothing as revolutionary as compiz might be introduced as an alternative to the new gnome).
So finally, Gnome-Shell made me think about switching to simple Window Managers like OpenBox or similars, or just using compiz alone with some small panels and the things one might need.
I really liked Gnome, but I do not like the path they are taking - small things like gnome-mount (which sometimes prevents you from mounting several USB-sticks at once, and does not give out ANY information when you call it about what it has just done - or hasn't done), nautilus (which draws the desktop AND is the file-manager - reminds me of windows) or the gnome-"registry" gconf, which looks far nicer than Windows Registry, but still is something that could have been solved otherwise - those small or even bigger things are there to integrate gnome "into itself", but also cut off other programs that don't join in.
So, for me, let's wait and see and try out all the other options we still have! Finally, a desktop should be individual!