In this case, it's not quite as subjective as usual .. the icons in that shot are not consistent in terms of color usage, perspective or lighting. Even emblems on the icons are not consistently rendered / placed.
It really looks like a half-finished icon theme, or 2-3 themes that were mashed together in a blender. There is nothing subjective about those things: they are measurable.
Whether it matters to you or not is another matter. Some people don't notice such things at all, but the vast majority of human beings do, even if they are unable to point out the "what" of the thing that bugs them.
The alignment of items in that window is also just HORRIBLE (another measurable thing fwiw).
The subjective question, really, is: does that new yellow folder look good?
I'll bet most people will react negatively to them due to the choice of insipid yellow, trying to make a flat 3D object (which is an oxymoron), the lack of symmetry in it, and how poorly it works with overlays. But, that particular issue I will admit, is rather subjective.
The rest, not so much. That screenshot is measurably horrible.