It's no wonder why so many adults I know (mainly guys of course, including myself) like this anime cartoon. I would discribe it as the UFC in cartoon form, and I wonder if the last fight in MATRIX REVOLUTIONS between Neo and Smith was inspired by Dragonball Z. This anime has testosterone and adrenaline. It also contains spiritual/metaphysical teachings and a little humor on the side to lessen the emotional tension of the scenes.
More detailed info about the DB universe later for those of you who are new to it, but for now a couple of youtube videos.
EDIT by admin 6-25-2011. For a negative view of DBZ see this post: DBZ's interesting theme Dragonball Z