If you've seen any promos for Steven Universe, you probably assumed (as those promos seem to suggest) that it's your run-of-the-mill kids cartoon with doe-eyed children and animals and maybe some strange characters, but basically a kid's cartoon.
Oh boy are those promos deceiving.
Steven Universe's backstory is about a group of sentient genderless stone-based super-powered aliens (called Gems) who arrived on Earth thousands of years ago to mine it for resources, but when they discovered it was populated a group of them decided to defect in order to protect the indigenous humans, and started a long and bloody civil war - which they ended up winning, but they were stranded on the Earth and so remained to protect the humans from whatever may come (which ended up being a lot of remnants from the war). Those remaining Gems - who also happen to live on a geological time-scale (meaning millions of our years is one lifetime for them) settled in what seems to be east-coast USA.
Fast-forward to the 1980's where one of the Gems (and also their leader) called Rose Quartz fell in love with one of the local humans - Greg Universe, a washed up self-proclaimed rock-star.
It's at this point that it's worth mentioning that while the Gems are technically genderless, they're all represented as female and use female pronouns. This is where it starts getting really interesting.
See, after Rose and Greg fall in love Rose gives birth (and in the process gives up her physical form - meaning that she turns back into her 'gem' form) to Steven, who inherits her gem and her powers. After a few years with his father, Steven moves in with the rest of the Gems ("The Crystal Gems") to start learning to control his powers, and that's where the series actually begins.
But there's so much going on in this series from all characters, and they're all equally interesting.
The Crystal Gems are Garnet - the big (and later revealed to be very VERY special in ways I can hardly describe) leader of the group and also the muscle, Pearl - who's portrayed as more of an intellectual, dancer and sword-fighter, and Amethyst - a shape shifting teenager-ish omnivore (she literally eats everything).
But here's the catch, and what makes Steven Universe so different and interesting.
Pearl was Rose Quartz's right hand - and was MADLY in love with her. She believed that Rose loved her too, until Greg. After Rose died to give birth to Steven, Pearl never really recovered and still suffers from pretty intense PTSD.
Amethyst was created on Earth by the homeworld Gems as a fighter - she was basically a weapon - and though she was freed by the Crystal Gems and reclaimed her own identity she has serious self worth issues, bordering on nearly suicidal depression. She at one point flat out says that she hates herself and never asked to be made, and wish she wasn't.
Still think it's a fluffy kids show? (Fans refer to it as "The Singing and Crying Show").
But it's not all doom and gloom - the show has TONS of SUPER positive messages: firstly, the Gems are all technically genderless but presented as female, and they're badass. For one, it's empowering for girls, but also it fights gender-role stereotypes by completely removing gender-roles. For example, Steven befriends a smart nerdy human girl who later learns swordfighting and appoints herself "his knight".
It also completely normalizes same-sex and gender-fluid relationships, by not only making nearly all of the romantic relationships in the show between Gems (and thus all homosexual), but they also introduce another aspect which I'll touch on later - because it's kinda of a spoiler.
Additionally, it really touches the issue of body image in a really favorable light. Steven is chubby and loves food without shame, Amethyst is very full-bodied (despite being a shapeshifter who can take whatever form she wants) and eats EVERYTHING all the time and Rose Quartz was HUGE and GLORIOUS.
This show touches everything, without shame - body image, self worth, depression, love, heartbreak, war, death - even to some extent (albeit only implied) sex and even sexual assault.
Which is where Garnet comes in... (spoilers ahead)
See, in the Gems' race there's something called "Fusion". It's not sex, it's not even 'lovemaking' - but it requires two Gems to be perfectly in sync with each other, and makes them both fuse into one being which is a combination of both of them. It is very intimate and frowned upon in the gem homeworld, but it allows gems to combine their powers in creative ways, in addition to just becoming bigger and stronger.
Late into the first season it is revealed (after being heavily implied throughout the series) the Garnet herself is not just one Gem, but the result of a nearly constant Fusion of two very much in love Gems called Ruby and Sapphire. Their relationship throughout the series, once revealed, is portrayed as a very mature and very healthy relationship - and while they do fight once or twice, they always make up by understanding each other and hearing and talking. Basically, they love each other so much that they can't stand NOT being one with each other. Which is what makes Garnet not just one person, and not two people but as she herself puts it - "an experience" and "a conversation".
It's important to point out that while very intimate, Fusion is NOT sex. But it's analogous and presented in such a way that if one was to interpret it as sex - it's passing along all the important messages about intimacy: It HAS to be consensual! It's very personal - and while frowned upon by the 'old world', there's absolutely no shame in it whatsoever.
To sum up, Steven Universe IS a kids show, but it's the kind of kids show that's bound to create a better generation. It's also a show that many adults (including myself) completely lose their shit over, in a completely emotional and personal way, both because it touches so many universal and ageless subjects, and also because it just makes me so damn happy and proud to know that kids today have such a brilliant and diverse medium to look up to and be influenced by.
It's definitely not for every adult, it's more kid-oriented than more adult action/adventure cartoons like Avatar: The Last Airbender (in fact I'd say it's more of a cartoon than an animated series), but if you can stomach the more childish aspects once in a while, it's really something else - and something good.