I am, and thousands of other people I met in my life, a big fan of this series. I might be a little biased since I come from a generation that grew up watching this but the truth is that the story, the characters and the soundtrack are still some of the best in the genre.
Kabamaru's story is a comedy from start to finish with laughs guaranteed at every episode. It is reminiscent of Ranma 1/2 in many ways but it has its own unique flavor. It has it all ninjas, school romance, comedy, impressive fights and did I mention ninjas. Without giving too much
away I would only like to add that the story is two-fold. One story revolves around the schools rivalry and the other story focuses on the friendship of the two ninjas.
The problem with Kabamaru is that all characters are likable. Even the evil ones are just too funny to hate. All play their part very well in this story and every episode links them closer and closer together. You can't help but laugh at the simple minded Kabamaru and his everlasting hunger that is tied to his strict grandfather trying to make him a better ninja. After you watch this you will think of him when you are starving for some food after a long day. Mai is the adorable kind girl that everyone loves and keeps Kabamaru in check through the series. Shizune is odd by having a kind face that hides his cruel mind. The two grandmothers are like day and night but equally funny and with their own stories contributing nicely to the whole plot.
The anime is quite old so the style of drawing reflects the 80's period with simple lines and not much variation in color. The simplicity actually makes it appealing and makes the comedic faces stand out much more.
While nothing special it is very memorable. I still can't help smile if I hear the OP song somewhere. Try googling "Kabamaru OP" and tell me if the music doesn't get stuck in your head. Classic 80's. I thought the filler music is plain but very well suited for the variety of situations it is used. Too bad there was no variation.
It is definitely something worth watching. There are no filler episodes and none of the characters are wasted. I would highly recommend it if you can find it. There is nothing like it for sure.