This game is for AC vets only...
The gamespot review is a bit wrong. While you do start out with a large number of parts, the best parts in the game must be unlocked. You will gain parts by beating training missions and advancing in the arena. Since the training missions (minigames) are challenging, there is a real sense of accomplishment when you earn a gold medal.
If you are new to this series, you should probably avoid this game, because it offers no real missions or credits like a standard armored core game. Some other armored core games, like AC3 or AC:Nexes are much better for beginners.
However, for vets of the series, you might just find yourself playing this one for hours on end. I know I did. This game can be easily found for under $20, making it a great cheap thrill for vets of the series.