What he's referencing is displays that are meant to display the UI at twice the pixel density. It will run just fine on the macbook pro with the retina display,

What he's referencing is displays that are meant to display the UI at twice the pixel density. It will run just fine on the macbook pro with the retina display, but it will run at a 1:1 density instead of a 2:1 density (which is what it's designed for). Here's a little image I drew quickly to illustrate: http://i.imgur.com/4gizfp0.png http://i.imgur.com/4gizfp0.png On that screen size, OSX will appear like the top image on a non retina display, and like the middle image on a retina display. Ubuntu will display like the top image on a non retina display, but will appear like the bottom image on the retina display.