It is built on top of layers of abstractions and loosely coupled code to make building application front-ends simpler. It avoids using vain effects, styles or images that do not contribute to the function of the application.
Flakes is different. Well designed from the ground up. An uncluttered interface that lets you get work done without jarring your sensibilities. Responsive so you can manage your business on the go. Built around a component architecture for easy development. And much more.
In my opinion it is very ugly, becouse it is only black and white.