Old and new, New and old.
Gameplay: Absolutely perfect. Stomping a Goombas brings old school gamers back to the old days of gaming. It also has some new features: The Shell item has the ability to make Mario (and Luigi) turn into a shell and slide forward, hitting enemies on the way. Most attacks cannot damge you. But you can surely kill yourself!
Mini Mario (Mini Luigi if you use Luigi): When using the Mini Mushroom (or Poison Mushroom, whatever) you will be tiny and can go faster than the standard state. When you jump in this form it takes Mario (and Luigi) longer time to land. Mini Mario (and Mini can stand on water (I think) too. But the Mini form is really weak. Get hit once and your donw for. You can only kill enemies in this form by doing a butt stomp. How to unlock World 4: Beat the boss of the last castle of World 2(the caterpillar wiggler like thing) with Mini Mario (or Mini Luigi). They will go to World 4.
How to unlock World 7: Beat the boss in the last castle of World 5 with Mini Mario or Mini Luigi. They will go to World 7.
Mega Mushroom: The most powerful item in the game. When you get this item, you will be HUGE and invincible for limited time. All the enemies who get in your way will be destroyed. This is my favorite item in the game. Classic Items: Recurring items. Super Mushroom: You become stronger.
Fire Mushroom: You can shoot fireballs. More recurring items are in the game.
Sound: Nice Music. Good Voice acting. But though the sound is good, I wouldn't give it a 10 because that is a little too high.
Clsoing Comments: Buy this and Sonic Rush if you want to start you DS game buying spree.