The Backyardigans rock
I really do love the Backyardigans. Musically it's great, and the stories are still funny enough for dads.

One of the comments below talks about the rhymes, which is a huge part of the appeal. Here's part of "A Challenge" from Born To Play, with Pablo assigning a task to Tyrone & Uniqua:

T&U: Will we have to find a princess, and climb real high to save her?
P: This challenge is much harder, you'll have to be much braver
T&U: Braver?
P: Braver, the importance is much graver
T&U: Will we journey to the mountains and chase a hairy beast?
P: The challenge will be tougher, or just as tough at least
T&U: Tougher?
P: Tougher and perhaps a little rougher

And from my favorite Backyardigans song of all, "Astronauts Never Give Up":
Uniqua: We took the astronaut pledge, the astronaut oath
Pablo: Well which one was it?
Uniqua: Pretty sure it was both