Why You Should Watch Avatar: The Last Airbender

I've recently returned to a second viewing of what may very well be my favorite long-running TV series: Avatar: the Last Airbender. This time round, I've tried to sell my roommates on the show, and results have been... poor. They find the show to simplistic, and too cartoonish. They are wrong. But my attempts to convince them that have gone astray, largely because their exposure to the show extends to whatever episode they happen to stumble in on. Spending five minutes explaining why Aang has hair now or why a turtle duck exists is not going to sell anyone (unless you're a very special sort of anyone). So I thought I'd set out a more detailed, exacting argument here for them, and for anyone else who is still missing out on this show. (I'm breaking it into three posts, 'cause it's really long.)