Such an effective design. I immediately recognize even subtle difference between icons at the lowest sizes. Meanwhile, today I get lost on my Android phone and in most desktop applications with low-contrast and monochrome icons.
Flat and monochrome icons have lost so much expressivity they are basically useless to express what they stand for. A lot of time I had to think for a moment while having the name of a menu written to make the connection between the image and the feature.
I recently had this problem after downloading the latest version of GIMP and becoming frustrated trying to decipher the default low-contrast icon set:
GIMP is my pet-peeve as well. I literally have to "read" each icon to find the one I'm looking for. Luckily you can change back to the color set, which is a lot better, although not perfect.