Fun to the last drop.
PEACH GETS CAUGHT. There has got to be a political reason why peach keeps getting caught. Well, whatever the reason, the Koopa King's Kid is up to no good with our pretty princess. The plot, like other Mario games, is laughably simplistic, but it's always been. Go through levels of land, sand, water, fire, ice, etc.; beat bosses; skip levels; unlock secrets; and do other Mario-esque tasks to get closer to the final level where (SPOILER ALERT) Peach is saved. I wish this game had a newer plot, maybe like a deeper involved plot like Paper Mario, but the classic formula always works well and never bothers.
MEGA SHROOM! Nothing but a level skipper. You simply mow down hinderences, even pipes and levels you may need to go to to get secret coins and stuff. Then, the meter gets counted and converted into 1-up shrooms. MINISHROOMS! Useless unless needed. Basicaly, you get really tiny. You can't kill anything, but you can stay airborn longer and get to tinier areas.
MINIGAMES! Yes, there are a few minigames to pass the time. If you're stuck on a level, just get bored (highly unlikely), or beat the game you have a few minigames to pass the time utilizing the DS's touchscreen. Games like sorting bob-ombs, drawing pipes, and three casino-style games are actually good enough to keep a single player enthralled even after beating the game.
SAVING. You can only save your game after beating a fort, castle, or paying 5 big coins. I know, you're probably thinking, WHAT?! But never fear, unless you get a Game Over, you can just close your DS and put it into sleep mode. Mario will say "See you next time!" and when opened he says "Itsa me-a Mario!" cutely.
OVERALL: A classic that has already made thousands buy DSlites.