This is a simple, fun fighter, classic in execution with great graphics.
The gameplay mechanics are smooth and will be intuitive for anyone vaguely familiar with the genre. You can get by with button mashing to begin with but as you try harder difficulty levels, one must pay more and more attention to you and, especially, your opponents are doing. To top this off, the graphics are impressive and immerse. While I feel that this does not offer true 3D gameplay--you can only move forward, backwards, up and down just like in the Super Nintendo days--the sets have great depth and the 3D affect does add something especially to combos and special moves. A small complaint might be that the backgrounds are mostly static but the rest of the graphics and gameplay are good enough that you really don't find yourself paying much attention to the backgrounds.
As far as plot and story, most of the character's stories are forgettable and they are not told through gameplay in any shape or form, just through cut scenes. The cut scenes are decent enough but since they don't affect a single scene, many gamers will find themselves skipping them. For single players, it'd be nice if there were a story mode a la Soul Calibur but the individual fights are exciting enough to make such a feature not entirely necessary.
The multiplayer mode is where the real addiction kicks. It speaks volumes about the gameplay when you find yourself really, truly angry at some random guy across the world for sneaking in a punch just before you unleashed the combo that was going to end him. And you don't get mad because you think the game messed up or the server lagged, you get mad because you know he beat you fair and square and there is a very good chance you'll never see him again if he doesn't deem you worthy of a rematch. You do wind up playing a few people who chose to spam specials via the easy to use touch screen combos but once you figure out a defense they are just fodder to pad your stats--unless they chose to run away. Online tournaments and leader boards would be fun but the one thing I think this game really lacks is an ability to find people you've fought before and challenge them again.
At the end of the day, while there could be more features added to this excellent little card, it offers everything you really need out of a fighter and more on a handheld system. It is hard to find reason to complain. What this game lacks, it makes up for by doing what it does really well.