I just finished the Saiyan invasion Saga. I think the game is good but the content is not detail enough for a huge DBZ fans.
For example, during the training in King Kai planet, the game offers no detail at all. It just use some words and a few video to show Goku learnt Spirit ball. I expect there will be a lot of fun stuff in King Kai planet, such as dancing and catching the monkey (YES, the game does not even mention any interaction between the monkey and Goku), driving King Kai's car, battling with King Kai, etc.
In the promotion, it keep saying that fans can explore more details (some of them are untold in manga and animation) in this game. So far, I didn't see any.
It will be much better if gamer can spend more time, instead of just randomly raising Goku's level by 10 when he is revived and go back to Earth to fight Vegeta.
I hope that there will be more details in the other sagas.