I started watching this when I was quite young. I'll admit that I was *too* young to understand the show, and yet I watched it. Maybe for the excellent art and animation. This show absolutely spawned my love of reading and adoration of books, which is why I have my own mini-home-library.
The characters in Arthur, with the exceptions of D.W. and Muffy, are lovable, relatable, and have realistic and endearing personalities. The colors are excellent, the animation is smooth, and although Arthur's voice actor had to change often as the people voicing him grew up, I never could tell the difference as a kid, and only now do I notice any change - slight as it is. This show has always been a comfort to me, and I watch it quite often even now, at the age of 21. As I say on most of the episodes to eleven-year-olds who claim they "still watch it!", if you were really mature, you'd be able to watch it without your age mattering. Arthur is one of those shows that true fans will never tire of. The characters and situations are mostly believable, and most are likable, too. The music is fun, as well.
My only issue with this show is that D.W. and Muffy both came off as spoiled, selfish, and relentlessly unpunished, even when they did something wrong.
On the whole, though, Arthur is most definitely worth watching - each episode features a lesson in giving, sharing, and basic morals, and some go beyond and teach about right and wrong even in the toughest of situations, facing fears, and growing up. Plus, being animated and colorful, it's just fun!