My children (4 and 6) love these shows. Both find the shows funny and entertaining. They ask to watch them, and then surprise me with the facts they recall and the connections they make between the show and observations from real life. We've been talking a lot about science recently. My six year old becomes interested in learning more about the topics of episodes, so he's also been reading more nonfiction since we purchased these DVDs.
The only downside of the series is that it is slightly dated, with the episode on computers being the best example of this, and none of the episodes deal with wireless communication.