DBZ is one of the greatest manga of all time. The story revolves around some main characters that are well developed and fortunately, it gives characters that have been developed since DB a break(without forgetting them) letting new ones in the spotlight. The story progression has a basic structure which is mostly true for all arcs, Battle(s)/Training -> Battle(s) with evenly matched characters/weaker vs stronger characters -> Battle(s) rescuer vs bully/hidden potential unlock/all out match -> arc decisive end battle. That is a good formula indeed. The universe is an epic one even though dinosaurs co-exist with flying cars and the world governor is a rabbit. It never gives too much attention on a point but instead explores most of the options it has during battles or narrative parts. One thing many people mistake is that DBZ is fighting only. That isn't true. DBZ has a family friendly side that is expressed through comical moments. The fighting also has a reason, it always has a reason for example: for the universal safety. That is cool to know and also cool to watch. The characters all have different types of personalities and are suberbly developed. Goku, the main character, is one of the best characters in any manga. His growth since DB is visable, both in potential and in character. The artwork is great. Each character feels distinct without having a lot of differences. The art also combines huge energy waves with background enviroments and hand to hand combat nicely. Dragon Ball Z is a huge journey full of surprises, fun, epic moments and even some bad story points.
Dragon Ball Z. Simply it's about guys who use kung fu to fight invading aliens who want to destroy earth. Sounds kind of simple and sort of corny. Good thing the plot gets deeper and more incredible.
Story: Learn Kung fu. Protect the earth from invading aliens. Learn the truth about your origins. Gain super incredible powers. Eat large amounts of food. Shoot pure energy from your hands. Die. Come back to life. Do it all over again. That's just a little bit of what makes up DBZ.
Like all great shonen mangas, they're strong points are comedy and action. I recommened this for anyone who is really into that kind of stuff. If you get wowed at the beginning of DBZ, just wait, it gets better. If you don't get into it, try reading the later chapters. That's when the fights get even better.