For example, I find myself liking the activities overview more and more since it combines together functionalities that you'd have to access separately on other desktop environments, namely a keyboard based application launcher, windows scale (or exposé for the Mac crowd) and virtual desktop manager. It's problematic that each environment maxes out at 8-9 windows before it becomes unmanageable, but the philosophy seems to be new desktops on demand, which are quick to create (just drag a window to the blank desktop or middle click an application to launch it in a clean desktop)
And the new Alt+Tab behavior does have a silver lining in that it scales much better for large number of windows since it allows you to drill down much quicker to the window you're looking for: Alt+Tab until you reach the application, Alt+<above tab> to reach the specific window you want. Or Alt+Tab, then use the mouse to highlight the application and then the specific window.
Another little know functionality is that the shell comes with a screen recorder: Ctrl+Shift+Alt+R to start recording, again to stop, the video is saved as WebM on the root of your home dir.
It's far from perfect, some functions take way too many motions to execute, and I wish they allowed you to bind mouse shortcuts (it would be perfect to enter the overview), but the basis for what could become a pretty decent desktop environment are there.