It only provides some of the cosmetic look of Unity. It doesn't provide any of the functionality, such as global menu bars, keyboard controls, a dock with both keyboard and mouse controls, and so on.
You can't move all the app's menu bars into a global menu bar when the new UI guidelines means that GNOME-conformant apps do not have menu bars.
You can't have a search tool that searches menu trees that aren't there.
You can't have add-on status icons in the top panel when the developers have removed the APIs for add-on status icons and combined their own status icons into a smaller number (gods know why, but they have, and it sucks.)
You can't make intelligent use of title bars, for example optionally putting menus into the title bars, or hiding them for full-screen apps, when the GNOME guidelines say don't have a menu bar, use CSD and put dialog buttons in there.
KDE can fake up a global menu bar; GNOME cannot and the GNOME team actively seek to prevent such things.
But at least some of the things you enumerated should be possible to add. Maybe file an issue, see what happens.