This TV show is quite entertaining for both kids and adults.
For kids because there is a lot of action and a generally easy to follow plot. The main characters are a pretty nice role model, they are poor, humble, simple folks, and yet they fight hard for what they believe in. Even if they are minority and so few people acknowledge them, in good or bad times the Togakuri family will stay united.
For adults it gets a bit trickier. Most will soon realize the ambiguity of dialogues and plots that actually don't seen too well planned. Specially if you watch the translated (portuguese) version, you will often notice some lines were probably not carefully translated. For example the word for sign and inscription in the Japanese language, might be the same, and when they are making references to those 2 things at the same time (Dojo Sign, and half of the Insciption), they use the same term, which is pretty confusing. But thats exactly what makes it a very entertaining show for adults. If you have a silly type of humor you will just crack yourself up with this show =)
I never get tired of it. I have seen all episodes when I was young, taped many, and I still watch them back and forth when I need a good laugh.
Its very hard to find them on tape though. They were not a big hit in japan, and in Brazil its dimming away.
Hope this was helpful.
