You'll find a lot of people, myself included, that point to the 10.6 era as peak OSX aesthetics. I personally prefer "steel and grass," some people prefer space, the specifics vary person-to-person but a lot of people agree on the trend. Skeuomorphism has an uncomfortably high skill floor, but it has an astronomical skill ceiling. With Apple, it shows. It
really shows.
In contrast, flat design has a skill ceiling so low that it can turn the most creatively bankrupt troglodyte of a non-artist into a hunchback.