I still have MorphOS for Classic Amiga on my Amiga HD. I just don't
have Amiga anymore :-D
It was really cute system. You could choose to use Ambient or
Workbench (both equally bad

) but tools like KingCON are built-in.
I had MUI 3.9 PPC on it so it was very fast. Still nothing compared to
"real" PPC machine. But it was neat I could use some neat MUI features
in my apps not available for ordinary Amiga users :-D
Regarding app compatibility there werent much difference. For games
only system friendly software runs. No chance to play SuperCars II
from MorphOS for example (unless you use UAE).
But until MorphOS is publicly available for classic Amigas it is
vapour IMO.