Effects in GL mode work fine for me with the recent proprietary nVidia drivers (with "fine" defined as "not crashing", not "perfectly fluent" although I have a not-so-low-end GPU - I expected it to be as fluent as compiz/beryl, but it seems not that fast).

Maybe the devs should have just told the poeple earlier that 4.0 wouldnt be as useable... All of that countdown-media-hype thing just had expectations a little too high for the 4.0 release I think.
They did tell people, but I agree the countdown thing might have only increase their appetite regardless of what they have been told.