My son is 4 and we both enjoyed it. It was adventurous. It promoted good over bad. It also showed that "people" can change from bad to good. As the norm with the Backyardigans, they showed that we all need help sometimes and that working as a team, works.
My daughter and I watched Super Secret Super Spy several times since it first aired over a month ago. I love the show and I'm so glad they can make movie I look forward to another one in the near future and I'm sure my three year old daughter would agree.