I think it look really beautiful on a 1800p but not much difference from a 1080p screen because the size of the screen... the screen size of the Mac is small to show all the quality of a 1800p resolution.
In fact I think this demo of Rayman Legends is better than Rayman Origins because the art style... I liked it.
Regardless of its native resolution, trust me, everything looks better in that high of resolution.
And I agree that the art style in Legends is much more detailed and creative than in Origins. By the time it comes out, it will no doubt be the best-looking game on Wii U. It will also be tough competition for best-looking game on any console, in my opinion.