Princess Jellyfish was a real treat to watch for me, because it was very palate-cleansing. This show really stands out with regards to its characters. Tsukimi is insecure, looking to navigate the confusion of getting out on her own and, above all, not a high school girl. In general every character we meet has their own compulsions, quirks, neuroses and restricted interests, and the show feels human and believable because of this.
The main way the show draws its comedy is by showing Tsukimi's insecure, yet grounded personality engaging with these other personalities. In one scene, she may be following one of the Sisterhood's many zany schemes. Later, she might engage with the son of an important MP who tries to maintain an unflappable, distant demeanor, but is easily embarassed despite himself. Or a model who just has a complex for afros. Regardless of what's happening, it's a riot to watch.
The art style is a nice change-up too, quite a departure from the slick, young-looking designs of most modern anime. It doesn't feel too clean or too dirty. I also really liked the OP's love letter to American cinema, which was really unique.
I would call this anime a great example of how to do a slice-of-life. Rather than stale pervert jokes, an excessive focus on cuteness, and cliched romance plots, this anime uses mines the psychology of its characters to create funny jokes and down-to-earth, but interesting, conflict. The result is an anime that never has a dull moment that I can recommend to anybody.