Microsoft’s design language, Windows Modern, is eerily similar to the paintings of Mondrian. Its abstract world of flat colored planes and typography has lost all sense of connection to anything meaningful or concrete. These deliberately obscure design choices often leave users without any way to discern the function of interface elements.
That rings of unjustified bias. There's hardly any difference between Windows Phone and iOS 7+ in this respect.
IMHO Windows Phone is somewhat more logical to use and has less ambiguous UI elements for one reason: apps tend to consistently use the bottom bar for actions. The bar always works the same and the buttons always have the same style.
On iOS there's more of a tendency to sprinkle buttons anywhere on the screen, and those buttons can be styled pretty much anything: plain text, plain icon, circle-enclosed icon...
Still, that's a minor gripe in practice.