incoming rant
NSMB Wii is... eeeeeeeeh. I think I've come out the other end of it liking NSMB DS more, for all its warts. For the most part is really is an uprezzed version of the original with slightly more refined level design, and it's worse in some ways. The handful of enemy types in DS that were still a little bit dangerous (e.g. Bloopers, Fire Snakes) got nerfed, and the kind of interesting SM64 holdovers were axed in favor of dredging up more stuff from SMB3 and World in lesser forms. Stuff like the red coin rings and end of level flagpoles were also nerfed, removing even the pleasure of conquering those irrelevant challenges.
SMW's spin jump is back, but it can't bounce off of dangerous enemies anymore and breaking bricks is still the domain of the boring-ass ground pound, so like the also returning Yoshi, it's but a shadow of its former glory. There's some fun to be had in using the mid-air spin borrowed from Galaxy to pull off otherwise impossible maneuvers, but the game never actually asks it of you.
Powerup selection is better, although not without its issues. The ice flower is pretty awesome, putting the power of the old throwable white blocks in your hands along with serving as a way to make impromptu platforms. The propeller suit is easily the series' worst flight powerup, sporting all of a double jump and a momentum-killing slow fall; the flying squirrel suit from U is a much better implementation of the idea. It also isn't very common, so you're generally using one of the flowers anyway, or one of the propeller blocks scattered around for the sole purpose of making the suit redundant. Then there's the penguin suit, which kicks ass by combining the best attributes of the ice flower, frog suit, and shell suit. Unfortunately they don't exist outside of worlds 3 and 4 and the one ice level in 9, so like the tanooki and hammer brother suits in SMB3, the idea's a bit wasted. And the mini mushroom survived being cut and is more fun than ever thanks to the Galaxy spin, but it's also basically nonexistent.
The game's Big New Idea is rotation: Terrain rotates, platforms rotate, blocks rotate, pipes rotate, everything can rotate. And does. All over the place. It's inescapable. You'll want stuff to just hold still and stop fucking gently bobbing back and forth, and it won't. You'll want to get on with playing the game and you can't because you have to wait for the platform to rotate. When the game isn't rotating, it's overusing good old moving platforms like they're going out of style, so one way or another you end up spending a lot of time just standing around waiting for shit to get into position. It's devastating to the game's pacing. The lesser New Idea is the concept of obscuring the player's vision, and it's generally unfun. There's a selection of dark levels, but the only good one is the first, which is full of fireballs and invincibility stars to light the way. Then there's clouds all over the place, which mostly exist to get you to shake the controller even more than you already are and serve the exact same purpose as the fake walls. This game loves fake walls. They're everywhere, and nine times out of ten they're also signposted with misaligned tiles or distinctive textures like you're playing DOOM, but that sort of mechanic barely works in a 2D environment (Commander Keen is still best-in-class in that department). The best ones are the few that aren't obvious, or where the level designer manages to distract the player with something else at the same time, but most of them are very lazily placed and functionally highlight secrets instead of obscuring them.
And then there's little things, like how warp cannons are even more poorly placed than they were in NSMB DS, and how you're stuck playing as hatless Mario most of the time because lives are so plentiful and there's no way to toggle the effect off, and how shake and tilt functionality is shoehorned in like every other Wii game.
The game hits higher highs than its predecessor, but also lower lows, and in general you've already seen everything it has to offer.