I agree, Unity is a mess at now, and Gnome 3 and Shell has many things that I really does not understand they change something that evolve in years to a good standard (like Printer Setup) and create a new one that you cant define the default paper size, and so on (keyboard, nautilus, ...).
I found that girls like Unity, because its more beautiful than Mate(Gnome2 fork), Cinnamon and GnomeShell. My conclusion is limited to my limited users test (Some Friends, my Girlfriend and Sisters). At work (University), my Linux users was using Gnome2, and I just update to LinuxMint Mate 13, to get (Ubuntu 12.04 LTS inside), after the upgrade they have the same theme, everything working like was. period.
For some new Linux users at work (migrate from WindowsXP), I choose to install Ubuntu 12.04 with Gnome-Panel (Fallback), after some tweaks (install the old printer setup).
I had only one friend using GnomeShell, because he use Fedora, but with many extension, to get mostly what we have in Gnome2.
In my notebook I am using Gnome3 fallback, but I will migrate to MATE, because the reason which you say "performance".