GJ Club is a generic slice-of-life, slight comedy, with a very natural, subtle, understated aura. It also has harem and moe themes, making the characters indistinct.
The one — and only — thing slightly worth mentioning is its very subtlety, lightness, naturalness, reservedness, tastefulness, gentleness — which makes this anime slightly different, more refreshing than others. It makes the anime bearable and slightly appreciable.
Although the series can potentially be enjoyable, it can be hard to overcome the heaviness of being generic, being ultimately completely useless. The abundance of generic anime and generic themes is a common criticism, notable problem of anime.
I personally enjoyed the series during my boredom. The anime can be relaxing, soothing.