I have only seen two episodes, but I thought it was jaw-droppingly awful! One of the episodes was okay, but the other one... wow.
It starts off with Grandpa showing Caillou his secret spot, which Caillou loves. But then his sister wants to come, and Caillou says no, she's just a baby, and she starts bawling and he walks away. I wait for Caillou to learn a Very Important Lesson about not making your sister cry, about playing nicely, about sharing... and wait, and wait. It's never addressed again.
Then the plot sort of radically shifts, and Caillou takes out a library book and accidentally colors on it. He's scared to return it, and I thought that part was fine. Then he returns it and the librarian says "oh that's fine, crayon just wipes off. The book has a special cover."
I'm not saying the show should be super preachy... but SOME repercussions for his actions would be nice to see! He was super bratty to his sister and got away with it, and then he was careless, which is obviously not a crime but I don't think it's a bad lesson that being careless and ruining something that's not yours is not 100% fine and dandy.
LOL maybe this post makes me sound like a wet blanket or a super strict disciplinarian... I swear I'm not like that. It just seemed strange, and I did not like, the fact that he seemed to get away with everything: it's not a model I want my kids to see! And as I said, I have only seen 2 episodes and I don't think the other one was that bad. He did get away with things in that episode too (he spilled juice on his new t shirt, and then his grandma showed him how to tie-dye) but I thought that was a cute resolution. At least he learned something about the permanence of not being careful, as opposed to "don't worry about coloring on your library books, it doesn't matter."