Largely builds on the success of the original, while adding replayability and other great gameplay modes.
That said, I was a bit saddened to see that, for all its potential, MGA2 did not fully take advantage of its potential. Being able to choose your bosses in arena mode would have made the option more enjoyable. Also missing is deck-editing feature that would allow you to save different deck types... being as you spend a lot more time on deck management in this version, this would have made for a convenient addition. What's more, the story in MGA2 seem less organized than that of the first, nor did it mesh well with its predecessor. Perhaps things were left ambiguous for the purposes of future sequels, but I found myself wondering why a lot of details in the plot remained unanswered at the game's close.
Nonetheless, despite these flaws, Acid 2 is an excellent title for the PSP. If it's any indication, I'm just as excited for an Acid 3...