I started watching this show on Netflix on my younger brother's advice, and was pleasantly surprised that it wasn't nauseating girl glitter, but an actual good show, with interesting characters, engaging plot, and very good world (universe?) building.
To start with, the main protagonistic characters (Adora, Bow and Glimmer) are generally likeable, yet all have their own flaws and character arcs throughout the seasons. However, I was more impressed by how the antagonists were written (Catra and Hordak). And I loved how some characters bounced between sides because of following their own independent goals which nonetheless drove the plot. (Entrapta and Double trouble)
The way the planet's environment connected to the plot was also awesome. From the first season it is asked "what happened to the stars?" and this oddity is only really answered by the fourth season. This use of environmental story telling makes the world feel very immersive, and the layers of lore and history give the entire background setting deeper meaning despite, the show being quite different from any actual cultures.
If you are still reading this comment, I just want to take a moment to appreciate the (best) character Entrapta. The writers wrote her as someone on the autism spectrum, who is obsessed with the magical science on the planet. She was by far the most entertaining character because of her unrestrained joy, quirkiness, and (at the beginning) her distinct lack of morality. One of the questions not always asked in science is "should we". At the beginning of the show, Entrapta is only interested in the "can we", and actively creates dangerous death-robots and reality-ending-portals, which the protagonists have to fight against. However, as the series progresses, she learns to empathize with and love the people around her, focusing her gifts with technology to help them win the day. Honestly, Entrapta is the best reason to watch this show.