Shows that are good for the whole family are very, very difficult. Most of them are great for children and terrible for everybody else. The very concept of the "family" genre is generally a false pretense. However, Avatar is truly a show for the whole family.

Very few episodes, if any, can be considered filler. The homage and love of Asian culture is evident and will certainly provoke educational questions in a young mind, and the theme and learning lesson in each episode is more or less directly stated, but restrained enough that any child can take something from it and few adults will be irritated by it.

The world building isn't perfect, but it's damn close. The viewer is consistently fed enough images of the greater world that it's inner workings are plenty without evoking endless questions. Oh, it will evoke questions: "Why din't they just make an ice bridge? Why doesn't the avatar just fly everybody away?" It'll happen, but unlike many fantastical series, it won't ruin your experience. For example, my question (as always, at this point) is why aren't there guns? Why is the fire nation, a nation that has access to incredibly advanced technology and machinery, still using trebuchets on their warships? There's no answer to that question, but unlike most shows, I easily forget this question. In general, everything works cohesively enough that it's easy for an unreasonably skeptical adult such as myself to forget their misgivings and enjoy the story.

Oh my gosh, the sound design? It's perfect. It's consistently perfect. It's no easy task to make the process of manipulating water, fire, sand, rock, and lightning sound natural, and this show does it flawlessly. The fact that few people even think about the sound design is a testament to how convincing it is.

The story is good. Actually, it's REALLY good. I don't even want to take the time to dive deeply, it's just really good. The characters are great, the visual storytelling is superb. It takes you back to a time when animators drew everything. Sure, there's plenty of 3D effects and assets to help out, but this show feels genuine and innately human in its animation style. I can feel the time that every frame took, and that's important.

Overall, as far as American TV-Y7 rated shows go, this and Spongebob Squarepants have to be the best. Seriously. Give it your time, you won't be disappointed.