I've been using it since the beta & it runs very well. Netflix & Steam install very quick & easy & run well.
This is my longest experience with Unity & I've found it's not too bad, either. Experience with OSX helps get used to the non-menu way of selecting a program but in use it's really like a menu, anyway. (click the Ubuntu logo thingy [or super-a] -> apps -> internet -> firefox) And at least when you bring up the program selection it doesn't cover the entire desktop.
I also like that they are trying to conserve vertical space by putting the launcher on the left edge instead of the bottom and eliminating the menu bar on windows. Moving the menus sounded odd 'till I learn why and , again, experience with Macs helps get used to it.
But Unity is slow compared to other desktops, and very difficult to customize.
I may still go back to XFCE just to get the 'right-click on the desktop for a menu' back. (or I could just install Windowmaker... hmmm)
But overall Ubuntu 14.04 has been very stable & runs quite nicely.