There's much more to this game's charm than simple nostalgia, however. Anyone with half a heart will absolutely fall in love with the characters, the graphics, the dialogue, the old-school shout-outs to previous games, the little visual effects lingering in the skies of every world... the love just keeps plopping out of the speakers at an incredible rate. For every annoying, excessively long fetch quest or mundane puzzle, there's a huge, cutesy payoff that makes all the trouble worthwhile.
Two quick examples: Early on you're saddled with a million dollar debt. You're supposed to work it off by running in a hamster wheel for about 20 minutes straight. Then you find a way to cheat the system and sneak by with only 10,000 bucks, just in time to watch the bank teller literally explode in shock.
A little later in the game you're searching for a piece of sacred parchment. The investigation spans an entire moon, takes most of level 4-2 to accomplish, only to have someone wipe their butt with it in the end. Honestly. The dude uses it for toilet paper. Some might get a little pissed, but we thought it was damn cute.
But if you want to get super technical, these aspects aren't all that different from Paper Mario 2. It was cute, overlooked and all that too, but other than a side-scrolling presentation, what's Super Paper doing different? Well, there's this whole "changing the world's axis" thing to make the game feel completely different from, well, almost anything you're playing today.
So you're running through a normal Mario level. Seen it a lot, probably. But with the push of the A button, Mario can move the viewpoint behind him and see this flat, 2D world from a whole new perspective. It seems simple and gimmicky at first, but there are so many creative uses in this 20+ hour quest that you'll be dying to invert axis the next time you bust out a 2D game. (True story - one editor went back to playing Symphony of the Night and had to re-adjust to the static side view.)
By moving the screen, impassible walls are just paper-thin shreds that have no depth and can easy be passed. Enemies that spanned the whole screen are now pushovers. Bottomless pits now contain caves that go "into" the screen and come out somewhere else. It's hard to describe, but the first time you switch views and see out into Mario's world, you'll totally understand.