Answer:
I do believe that the hardest part of an art critique is all based on opinion. Some have trouble with finding flaws, some with finding the good things. It all depends on you.
Interestingly, all of these subjects are combined in linear perspective, which uses geometric lines and a vanishing point to give the illusion of depth and space to painting. Giotto, Brunelleschi, and Alberti experimented and/or wrote about linear perspective and helped pave the way for future Renaissance artists.
