I have tested Unity myself. My
: Unity is basically a GNOME Shell Lite with Ubuntu theming. It is tightly integrated into Mutter, just like GNOME Shell. It has right-click menus that look like versions of GNOME Shell's with different coloration/transparency (e.g. Mutter's RGBA).
Which reminds me: I had a dream (which might be real in the future) about a modified GNOME Shell with Ubuntu decorations. Now I'm thinking the Unity decorations might be ported to GNOME Shell - we'll see how that works.