The game could be MUCH better, but it isn´t that bad either.
The problem? the characters. They left out vital characters, and put only one version of each one. For instance, you can only play Majin-Boo in his first appearance. What if i want to play him in his final form, or when he absorbed Gotenks? simply i cannot. They made characters who aren´t cool, such as Videl and Chi Chi. What are they doing here? i don´t know. Where are the phase 4 Super saiyans? i don´t know either.
The rest of the game is quite good. Decide yourselves.