What makes a good kid's show? If it engages my child and teaches him something along the way, it's good in my book. If I can stand to watch it myself, that's an added bonus.
My son loves this show, loves the characters, and it helps him understand complex concepts - not just math, but how things work behind the scenes. I guess it's kind of the geek's kid show: teaching how to diagnose and resolve problems in everyday life using math and critical thinking. Who knew following around a tiny team of handy-people (essentially they are the city's plumbers, pest control, maintenance crew, etc.) could be made this fun and interesting. And the fact that I can watch it with him and not find myself annoyed is a HUGE plus.