My main complaint is the all-too-obvious attempt to be politically correct. Besides all the family and ethnic stereotypes, all of the unusual or "cool" heroes (astronauts, zoo-keepers, doctors, nuclear physicists) are all women while men fill the more mundane, everyday roles (bakers, gardeners, garbage collectors). I just think it's weird and silly to try so hard.
The other thing that drives me crazy is the animation. The character's arms disappear whenever they are at rest. If you haven't noticed this, keep an eye on their arms. When someone puts their arms at their side, the arm gets sucked into their body and leaves only a hand sitting on the side of the character. It's strange, distracting and makes me think that the animators could have tried to perfect their technology before making hundreds of shows.
All in all, I don't think this is a terrible show, but I don't like it as much as others. I think it teaches kids some valuable lessons (positive thinking, respect for others) but also implies that every kid needs to find an adult or "hero" to solve every single one of life's problems. I"d like to see the kids (or Pizza Guy for heaven's sake!) succeed on their own every once in a while.