Adventure Time is not a cartoon for kids that is also for adults. It is a cartoon for adults that is also for kids, and therein lies its genius.
The show takes place in the colorful Land of Ooo. Everything is happy and bright and there's a Candy Kingdom and people are made of candy and this is awesome, right? Well, take a glance at the very first shot of the opening credits and pay attention to stray bits of dialogue and flashbacks, and you realize that this magical land is actually a post-apocalyptic world. There is not a huge amount of worldbuilding, but it's there, and it's always intriguing.
This complexity extends to the characters as well. Finn is a hero who loves helping people, but he can't help everyone. Jake may put up a lazy gadabout exterior, but he takes his responsibility for Finn seriously. Princess Bubblegum engages in mad science but must also consider what is best for her subjects. The Ice King has a nasty habit of kidnapping princesses, but it's just because he's insecure and lonely. Marceline is a vampire bassist, but she also has daddy issues. Lumpy Space Princess knows that she's so lumping hot, but she wants her parents to accept her. It's hard to imagine, but these characters are actually more three-dimensional than they look.
I love Adventure Time for many reasons. I love that Finn genuinely likes helping people, that the main character of the show has an unsullied, pure heart. I love that Jake has stretchy powers that are used more creatively than I have ever seen (Mr. Fantastic ain't got nothing on him). I love that Princess Bubblegum is a scientist princess, showing young girls that being a strong, intelligent woman and being a pretty pink princess are not mutually exclusive. I love BMO, the cutest little video game machine you ever did see.
I love...I love that I am finding it impossible to write a coherent review of this show because it is so delightfully incoherent. But that is a lie. Everything in Adventure Time makes sense in that world. It can be very surreal at times, as if the writers are just slapping together a stream-of-consciousness sequence of events, but with few exceptions, I don't think that's the case (some episodes are weird even for this show). They've created a world where a talking peppermint can coexist with a Hot Dog Princess, where a lemonheaded tyrant can coexist with a saucy, pie-baking elephant, where Lumpy Space Princess...exists. And they're able to do it in tightly written ten-minute episodes. I never knew you could tell such great stories in ten minutes! The episodes don't feel rushed at all; they actually have time to breathe. It's pretty impressive. And although the show isn't very serial at all, it does introduce more and more serial elements as it goes on, which makes it even better.
One of my favorite things about Adventure Time is its use of language. There is a certain hipster sensibility to it—hence my assertion that it is actually targeted to an older audience, despite being perfectly appropriate for and enjoyable to children—that can sometimes feel a little grating, but I love how natural all the invented slang is. "What the math?" is an actual thing people say. This is a show where Finn shouts, "YOUTH CULTURE FOREVER!!!" and it's goddamn hilarious and appropriate. Although most of his exclamations are just brilliant nonsense. The whole show displays a very playful outlook on language and makes the most ridiculous combination of words and/or syllables sound perfect. Not to mention the times when it just has characters spout Dadaist koans we imbue with our own meaning.
Thankfully, the voice actors perform all this nonsense with great aplomb. I was particularly impressed with Finn's voice actor, who manages to not only find different ways of shrieking as a battle cry but also make it endearing rather than annoying. The show also attracts a lot of great guest voices, from Weird Al to George Takei. Plus, many of the cast sing, and Adventure Time has some very catchy, entertaining songs, some of them rather emotional.
Emotional? Oh yes. Anyone recommending Adventure Time these days is basically required to provide the following warning: this show will destroy all your feelings. It doesn't seem like it would. And, no, most episodes are just hilarious good times. But every now and then, it will surprise you with unexpected emotional devastation. Also, warning you won't help you. I thought I was prepared but I wasn't. THERE WERE TEARS.
I could write so much more about why I love various episodes of Adventure Time and how much I love nearly all the characters, but I didn't know much at all about the show going in, and I've probably already said too much. It's a bit uneven at first, but it then it really hits its stride, and then seasons three and four are really good. Season five has been great so far! It's okay if you're still skeptical after this review, but I think you'll be pleasantly surprised at how much this show has to offer.
In conclusion, this surprisingly smart show is truly obsessed with butts.