Definately only for die-hard DBZ fans.
However,I am a DBZ fan and that's why I enjoyed this game,because I enjoyed seeing some of the DBZ characters and using Goku to fight against the DBZ villains such as Raditz,The Ginyu Force and Frieza.
The game is so short,you could complete it in 3 hours
The best way to play the game is to use shoot and run tactics,because Goku's melee attacks are so weak(even when he's highly levelled),and any enemy can inflict a lot of damage on Goku if they hit him with just one attack.So,the best way to play this game is to shoot ki energy blasts at enemies and run/fly a safe distance from your enemy and repeat the process.You will learn the kamehama attack which does a lot of damage to enemies,but only has a short range.You can make Goku fly,but only for a limited amount of time.
You gain experience points from defeating enemies and enemies respawn when you re-enter areas.
I like how the game lets you explore inside buildings and you can travel through the forest,city,on a starship,on Namek and the city has a good amount of detail with good road layouts,cars,buildings and people everywhere and Namek has the bluish green grass and weird vegetation and Namek style buildings.
The game shows emotional story elements such as how if you talk to some Namek kids on Namek,one of them will tell you Frieza killed his parents and he will beg you not to hurt him and he will cry and seem scared and it's hard not to feel bad for the guy,especially if you know what a cruel tyrant Frieza is in the TV show.
You'll get to use Goku when he's a Super Saiyan in his battle against Frieza and it was cool seeing Goku's bright gold hair and when Goku's a Super Saiyan in the game,it allows him to fly much further(which is a big advantage in the game).
Just like in the TV show,when you're battling Frieza,you'll see the lava reaching the surface before Namek is about to explode and it looks epic.
The game has some full motion video too.
Overall,the game doesn't have enough depth to appeal to anyone besides DBZ fans.But if you're a DBZ fan,you can find things about this game to like.