When Canonical decided that Ubuntu would have a new user-interface, "Unity," to replace Gnome 2, there was a lot resistance and discontent in the Ubuntu user community. Gnome 2 was a drop-down (or pop-up) menu system, harking back in a general way to the familiar Windows interface.
People who didn't like Unity could easily just go on using Gnome 2, at least for the foreseeable future (and switch to MATE after Gnome 2).
But the other alternative was to use Gnome 3, the official successor to Gnome 2. Gnome 3 and Unity have quite a lot in common. In fact, and it's clear that the Unity user interface is - broadly speaking - based on the same thinking as Gnome 3 about where user interfaces might be going.
As is documented in this blog, I was willing to give Unity a shot, and I even quite liked it. But I had a lot of technical difficulties with Unity, so I decided to try Gnome 3.
Now I've been using Gnome 3 for nearly six months, and I'm very much at home with it. And I'd like to put in a good word. Recently, I had to work briefly with the old Gnome 2 menus, and I couldn't believe how slow and fiddly the old interface now felt, after being thoroughly used to Gnome 3.
So, from me, at least, a gold star for Gnome 3.