I've heard nothing but good things when I went to pick this game up. Unfortunately that changed as I started to get into the game. The graphics are great, but really fuzzy, making some things a little hard to see. Also it's hard to play. The game isn't hard, the controls are hard, so hard that I fear many will be drop this game, and pick up something else, such as Mario Kart. But, the controls are tolerable, and you will get use to them, eventually. It actually feels like you are playing with a key board and mouse with this game. But you'll still feel a twinge of discomfort, as it's a really cramped space between your hands, unlike on the computer.
The game is also very linear, and it loses some of that classic metroid feel. It also seems a tad short, and the repetition early in the game, can be unbearable.
However, despite all these bad things, the game is fun, and worth a rental in the very least.
If you don't have WiFi, or friends to play with, this game gets a 5/10. However, the multiplayer is where this game shines. And boy does it shine. 20+ levels, WiFi, several characters, different weapons, different modes, and bots, makes this game easily the best multiplayer in the Metroid Series, and rivals that of Mario Kart. You could probably even go and pick up this game just for the multiplayer! Overall, if your in just for the main story, then you may want to pass this up if you never played a Metroid game before. Metroid fans will want to play this, but only once or twice tops. But if you have a lot of friends, and time on your hands, then the multiplayer in this game could easily make this game one of the best on the DS.