Saying something interesting about children's programming requires a critical shift, acknowledging that we are not the primary consumer. Actually, for much of this media, I think parents are that target audience. Sesame Street cannot possibly be as educational as advertised, but great effort is obviously spent convincing parents that it is.
Well, here we have something that is educational in a narrow sense, but very well engineered for kids. Let's set aside the specification of the character set, the determination of the animation style, the jokes, the pace
What impressed me is how the synthetic world is placed. Suppose that a goal of the project is to introduce kids to the marvels of living creatures and systems of living creatures. Choosing the oceans is almost a no-brainer because of the diversity and strangeness of the creatures, plus the fact that kids normally don't encounter sea creatures.
Much harder is deciding how to span our world with theirs. Look at what has been done here. The representative of our world is a band of anthropomorhized animals. We explore with them and also get educated by them, but the emphasis is on exploration and care of the explored. The octonauts are headed by a sea creature, an octopus that oddly breathes air not water and seems the most human of the band. The group also — and essentially, I believe — includes 'vegimals' a further hybrid that blends animals and plants. We (the humans in the audience) are blended, folded into our representatives, and they are folded into what they observe.
Now look at the other side of the divide: the sea creatures are themselves anthropomorphized, but to a subtle lesser extent. They speak English to the octonauts; they have the same emotional vocabulary as well. But they are apart, of nature.
I cannot think of a more creative approach to the cinematic problem of bringing the world of the child to the world of the sea, in a way that carries observation and message.