I am the mother of a 2-year-old who loves "Higgy-tow hewos" as she calls it.
The show revolves around four preschool friends (a multi-racial group, by the way) who learn to call on the people of the town to help them, and in the process learn about different professions -- plumber, librarian, tow-truck driver, mail carrier. There are no superheroes here, just people doing their jobs and thus becoming heroes to the children to need their help.
I particularly like Fran, the squirrel who plays with the children. She is an adult voice in the group, who manages to point out flaws in their often outlandish solutions without hurting their feelings. (Twinkle: "We could get friendly mice in pretty pink tutus to fly in a spaceship..." Fran: "That's a very creative solution, Twinkle, but it would take a long time to train the mice to fly a spaceship. I think we need to find something faster." Twinkle: "Aw, pickles!") [Note: That's not an exact quote from the show, just the gist of some dialog.]
From the perspective of someone interested in the careers of actors and actresses, it's fun to listen to the voices of the various heroes the children encounter, then read the credits to see who it is. Camryn Manheim voiced the plumber in one episode; Kathy Lee Gifford was the mail carrier in another. Betty White provided the voice of Eubie's Grand-Mama in at least two episodes.
Overall, a show that my daughter and I enjoy watching together.