... it wouldn't be the first time Aqua style desktops have appeared for Unix systems. The problem normally is that they're playing the notes without understanding the tune and/or they just rip off the Apple look and feel, sailing so close to the wind as to invite a cease and desist. To me this desktop seems to tick both boxes.
I also strongly disagree with the contention that a single pull down menu is the best. Personally I'd be fine with it on a small screen since it maximizes vertical space but as the screen size increases it just becomes annoying - my app is down here but I have to move the mouse all the way up there to click something and then go back down again? It just becomes an annoying brain fart, disconnecting the user from the task at hand. It has been tried on Unix too, most notably in the Unity desktop for Ubuntu and it just didn't work.
A better approach would be a more task centric UI toolbar and the menu is some kind of hamburger icon on the side. An app could even do what Firefox does - toolbar / hamburger by default but tap ALT and a traditional menu appears.