A lot of the examples on their front page I flat out disagree with, both because I hate the aesthetics, and because it represents user experience issues that I or my peers have frequently run up against.

For example, borders: I would argue the "more borders" example has it the wrong way around. For users with poor "computer familiarity" (e.g. elderly) the difference in tone isn't always as obvious as it might be to others as their eyesight is already poor. The use of borders then allows a clearer division of shapes without having to commit to a fully high-contrast solution.

(also the no borders version looks very silly, but that's just my taste)