They say developers don't know what to do with a Nintendo platform until Nintendo comes along and does the hard work for them, and with games like Super Mario 3D Land, it's hard to argue with that statement. More than any other game I've played on the 3DS so far, this game not only makes me want to keep the 3D enabled, it makes me want to crank it all the way up.
The 3D is used effectively throughout the game, and at times, it's even used to present optical illusions. Often, you'll find yourself running straight at the screen, or an enemy might leap out. While these might be seen as cheap tricks, they're used sparingly and to great effect. A late course in the game has an extended rollercoaster sequence that really shows it off. If you have a chance to check this game out, you really need to see it in action.
SM3DL plays the nostalgia card often, but incredibly well. Plenty of elements from Super Mario Bros. 3 are present (Boom Boom, Airship levels, donut lifts, etc.) and I was pleased to see a lot of callbacks to Super Mario World. If you want to tap my nostalgia button, just give me a ghost house to run through! Despite my own inclinations, the biggest nostalgic element has got to be the return of the Tanuki Suit, even if it's neutered. No turning to stone? C'mon!
Played straight through, the eight worlds rarely offer much of a challenge - I had about 120 lives racked up by the end. However, if you make your goal collecting all of the star coins rather than simply finishing the stage, you'll have to do a lot more exploration and out-of-the box thinking. Some courses require you to have the correct powerup in order to acquire the star coins, others hide them in plain sight, but with no visible way to get at them.
If that doesn't provide enough of a challenge for you, once you rescue Princess Peach, you're given access to alternate versions of the eight worlds, with tougher enemies, remixed star coin locations, anti-powerups and some really nasty time limits. These courses keep a running tally of your best completion time, so if you want, you can speed run them to your heart's content.
It's a shame that Super Mario 3D Land didn't get released at the system's launch, because I feel that people's opinions on it wouldn't be quite so mixed. But missing a launch by eight months and showing people what the system can be capable of is far better than releasing the killer app for a system five years too late. I'm looking at you, Skyward Sword.