MPP is probably the best game of pinball you'll ever play, and you can't go wrong with what this game has to offer.
Now seeing as it's a pinball game, there really isn't a lot to it other than trying to beat your old score, right? Not in MPP. Sure you bump Samus around with the flippers, racking up points and such, but you can also play mini-games while flinging her around if you get her in the right spot. Such games are:
1) Blasting enemies in her combat form.
2) Discovering secret areas to collect artifacts.
3) Fighting Bosses.
When you finish playing each mini-game, you are awarded with an artifact, or part of one at least. I would tell you what would happen if you collected all 12, but i'll leave that to you to figure out.
The game also includes a Rumble Pak feature that you put in the GBA side of your DS. This is a great feature, because not only does it sounds like you're playing pinball, it also FEELS like you're playing on an actual table........well, sort of.
If there is anything to be said about the graphical quality in MPP, it's that it looks beautiful. The tables are surprisingly well polished, and everything animates smoothly, though there are some limiting animations in some of the boss fights. but other than that, it looks great.
I can not express just how outstanding the sound is. The music is made up of the original scores for the Metroid series, only remixed, and it sounds better than ever. Everything on the pinball table sounds just as great as if you were playing on a real one.
Overall, I would recommened Metroid Prime Pinball to anyone who is looking for a game to kill some time. Even if you hate pinball games, chances are you'd probably like this. Likewise if you're a fan of the Metroid series.