Collage dominates the aesthetic direction of Hidamari Sketch, careful use of pop-art patterns, photos, words in place of objects, and flat colours carefully creates a visually distinct appeal to the anime, that becomes its main strength - you could easily watch the anime with no sound and it would be watchable purely for the strength of its visuals alone.
Outside of its visuals, it's standard cgdct SoL fare: the girls all have very distinct personalities from each other, being very cute and likeable, and most of the plot centres around their discussions and interactions with each other. Whilst the events aren't particularly comedic compared to other examples from the 2000s such as Azumanga Daioh or Lucky Star, there are a few guaranteed laughs each episode, and the cuteness of the visuals and character interactions are appealing enough in their own right.
It is an anime that simply has some very nice visuals, though it can be said that it doesn't expand upon them enough, and interactions that are definitely enjoyable.