Rent it first, you'll thank me later.
On to the bad.
The control is weak. I'm pretty sure that if I made a giant saber toothed tiger robot it would be able to back up. The zoids in this game, however, cannot. Instead you have to turn completely around walk to where you wanted to be and then turn around again. Not cool.
The other big issue with this title is balance. This game is super hard (unless you're a blade liger). Even getting through the "easy" fights is hard. Easily one of the most frustrating games I've played. On the flip side, if you use a blade liger and just stay close to everyone and use your blade weapon the game is suddenly way too easy.
Granted I spent less than $20 on the game and it did have some nice moments but I'm getting mad just thinking about the time I spent playing it and that is why I'm forced to give this low score.