As a big fan of the DBZ series, I can't say that the effort put into this game was terrible. I just had higher expectations.
The game does well to capture the atmosphere of the Show. The characters sound like theya re supposed to and the places look as real as they can be. Character models have also been revamped so that instead of the 3D graphics, you get more of a 2D look which looks more like the Characters in the show.
The game however, gets boring after the first you fights. The new Adventure mode is like a gameboard. You pick a character and an allie(s). Then you have to reach certain objects by going on different paths. It sort of follows the show. The gameboards differ in the in the matter that you would vs. Frieza on Planet Namke whereas you would take on Buu on earth.
The control scheme is too repetive. The additon of fusions is cool but the overall fighting engine is too boring. You use the same combinations to do Frieza's death beem as Goku's Kamehameha wave. The layouts of the controls are a bit awkard, but luckily they give you the option to modify it.
You can still do world tournament to gain money and buy upgrades. I find buying upgrades frustrating because you get a lot of the same skills as you already have.
Overall, DBZ does not rank upon one of the better pure fighting games out there. That belongs to Soul Calibur and Tekken. But if you are a really big DBZ fan, this is worth a shot to say the least.