You can say a lot about the slow story progression and lack of Outers, but SuperS had a very strong emphasis on it's themes. You had dreams and some fairy tale stuff, obviously, but you also had the contrast between childhood and adulthood and people's different perspectives on it.
The first half had a contrast between Chibiusa's sweet and innocent outlook on life and a relationship developing with a magic talking horse. Meanwhile you have the nightmarish Dead Moon Circus' Amazon Trio, going to bars, checking out on potential victims of the week based on how attractive they find them before going out, (attempting to) seduce them, then attacking them in a way that reminds you of sexual assault. It portrays the world of children as something pure and innocent, and the world of adults as evil, filthy, corrupt, dangerous, and without dreams. The Trio don't actually care about dreams themselves until Fisheye starts to question their existence and it sort of becomes a pretty different take on The Little Mermaid. That's what I saw the last part as, anyways.
The second half features the Amazon Quartet, all of them with a case of Peter Pan Syndrome and a child-like cruel callousness towards all the suffering they cause (except maybe JunJun in that one episode). PallaPalla in particular has a pretty sadistic streak in her, but she always treated it like a game. Unlike the Trio, they *do* have dreams and cherish them above everything else. Including the well-being of other people and even themselves. They never want to grow up because they believe becoming an adult means you'll lose your dreams. Nehelenia herself holds these beliefs to an even more extreme degree and and literally says would rather be stuck in a mirror all alone forever than give up her dream and grow up. On a side note, she refers to the Lemures, the people who's dream mirrors she devoured, as "animated corpses." I kinda wonder if Ikuhara or Enokido were trying to tell kids that people who truly have no dreams are basically zombies, not adults.
Throughout all this, the Senshi never fear growing up, never lose their dreams despite having to put them aside for their duty, never fall for Zirconia's attempt to trick them into running away to pursue their dreams by themselves (and probably act like the Quartet, if Usagi seeing a vision of the other four girls as kids before meeting her illusion meant anything). Chibiusa in particular matures quite a bit through meeting Helios and all the random people she encountered throughout the season. They're all going to grow up together and make their dreams come true together.
I'm not saying SuperS is my favorite season, that it didn't have some glaring issues, or even that they pulled off everything I described perfectly. But I do think the way it stuck to it's guns on the themes it introduced is one of it's strongest points. If you compare it to Utena, you can really see how Ikuhara and Enokido dabbled in the concepts they later explored more in the latter.