In the post titled "GA is pretty much the best show this season isn’t it?", Kuro exhalts:

A slice-of-life show that is original, funny, entertaining and informative without being boring. That’s what my impression of GA Geijutsuka Art Design has been like. It’s pretty much the best show, comedy and entertainment-wise so far from the crop of summer anime, and I already am impressed by quite a number of other shows this season.

So far so good, and I'm inclined to join him, but then:

Best part about the show is how informative it can be, and from the first two episodes I’ve already learned some interesting bits of trivia just from seeing the characters talk about their lessons. []

This is the primer on the usual "I know it's good but cannot explain why" (I saw a V.decent teatrise on the phenomena at Kaedrin, but cannot find it anymore). I'm quite sure Kuro does not watch a comedy show because it's informative, but it's what he can blog about it.

What really seems to happen is a humorous take on various elements of arts education. The creators jump off things which may be somewhat exotic, like the spectrum of pencils, or may be mundane, like the orange's skin, and then either develop them or mash them into the gag. GA works a lot more with it than either Hidamari or Sketchbook did, at the expense of iyashikey content (that is basically absent in GA). The necessary exposition then creates the "informative" aspect onto which Kuro grabbed. But it is far from being the best part of the show, merely the basis for the best part of the show.