My decided lack of skill did not preclude me from the cleverness and joyful whimsy of the game's demo levels.
Full confession: I've never beaten Super Mario Bros. 1. Or Super Mario Bros. 2. Or Super Mario Bros. 3. The first time I laid hands on Super Mario Maker, I feared that my distinct lack of "skillz" would mean the levels Nintendo had loaded on the demo were beyond me.
Happily I was wrong. To be sure, my handlers were careful to guide me to levels that weren't horrendous, but I got the sense that Super Mario Maker can inspire people to create not just "insane" levels, but clever ones as well. For example, the first level I played (which at the press of a button doubled as a playable title screen as well!) was a piece of cake since I discovered a hidden vine in one of the "?" blocks that led me up into the clouds, down a pipe, and ultimately straight to the end-level flag and easily past what I was assured was a nightmarish monster of multiple Mario enemies stacked one on top of the other.

It's at this point that my instinct is to duck down a pipe and hide.
I was also directed to another level, this time underwater, where I was told to "do nothing." The level was essentially one large Rube-Goldberg machine to automatically transport Mario from the beginning to the end. Automated platforms would truck me around the level, leap from track to track, and catch me before I fell off the stage. Deadly enemies would leap out at my uncontrolled character only to be blocked by a separate well-timed event within the level itself. Finally, after the level had repeatedly shown off how it could maneuver my still-uncontrolled character under and over deadly hazards, it deposited straight to the top of the flagpole. Whimsical, clever, and completely accessible for people like me.
I'm excited about the idea that this won't just be a game for the best Mario players, but also the many players who enjoy the franchise maybe even more for its secrets, surprises, and warp pipes. But I suppose that will depend on the custom levels the community creates. We were told that NCL was really behind the preloaded levels of the game, though Nintendo of America's Treehouse division had originated the famous levels (both insane AND clever) featured in the Nintendo World Championships earlier this year. (Thankfully Nintendo will calculate challenge levels for levels you browse online so you can know whether a level is actually hard before you play it, or if it just looks hard.)

Using Amiibo to unlock special power-ups adds costumes for other Nintendo characters to the mix!
An anecdote about the hours of effort in creation, play-testing, and re-balancing it took to create the Nintendo World Championship levels just went to illustrate how complex and precise one could get with the level creator.
It also made the level-editing mode quite difficult to show off in a limited amount of time. I could easily imagine spending hours on a level trying to choose the right enemies to stuff into a "?" block instead of coins, or trying to place blocks and obstacles just so to create the desired difficulty for whoever would play my creation. But even just within the limited time of my demo, I got to use the Wii U GamePad to not just drag and drop enemies, but apply powers to them (Giant Bloopers!) and shake them to activate alternate versions (Giant Bloopers with Baby Bloopers trailing behind them!).

Check out the theme selection along the left, and the "undo dog" and rocketship eraser in the lower right.
Of particular interest was the ability to, with a tap, change the entire "thematic" of a level from Super Mario Bros. 1 all the way to New Super Mario Bros. You could even choose sub themes within the game, like one that transformed blocks in an entire level to look like the Super Mario Bros. 3 airship. This wasn't only a cosmetic difference, the theme of a level dictated physics and abilities. The game couldn't magically re-arrange a level to account for added wall-jumping abilities in New Super Mario Bros., nor could it re-space jumps for the way different games worked, so I imagine the thematic of a level would be an important decision for creators.
Super Mario Maker definitely had some pleasing and/or challenging demo levels, and I just barely scratched the surface of what I suspect is a robust level creation mode. But I walked away with a different thought as well: Super Mario Maker could be called "software" or "a toy" as much as it could be called a game. This isn't just a challenge-machine that gets more hardcore with user input. It's also whimsical and exploratory and open-ended.

This robot bears an uncanny resemblance to a fellow I once knew in Mario Paint.
I don't think it's mere coincidence that Super Mario Maker has so many UI throwbacks to Mario Paint (a rocketship that erases levels, a dog icon/character to undo recent edits, and a level screen which has each icon contained within the frame of the save/load robot from Mario Paint). Like that earlier Super NES creativity title, Super Mario Maker seems like another unique attempt by Nintendo to explore new relationships between the player and the experience, be it called game, software, or toy, that will be piping out of the Wii U.