Really, it's quite unfortunate that the NSMB games were just so dire, so lacking and so painfully boring and stale in regards to their entire package with their art style and presentation; because how good the level design was I think has been overlooked. I don't believe we would be hearing pretty unanimous "best 2D Mario since the SNES" as much as we have because this to me feels far behind U in a lot more categories than advertised.
Like sure, I'm glad we finally have a 2D Mario with more bold design presentation than a licensed brand T-Shirt you'd find at Target but I don't think that alone compensates for some of the stuff that really I think a 2D Mario game should have been much better at.
I actually want to push back against this, because I think the problem with NSMBU comes down to more than just presentation.
It's part of it, absolutely. Leaning so heavily on the mold set by NSMB and heavily reusing NSMBWii music, especially when NSMB2 did much of the same just a few months prior, robs the title (and the subfranchise) of a better sense of identity. But it's not just the graphics and sound that feel derivative - it's the levels, too. Sometimes you get a Waddlewing, or a Fliprus, or a Dragoneel, and those new enemies or course elements make for interesting and engaging levels. But NSMBU suffers because it has so many courses that feel derivative of ideas from NSMBWii.
Let's talk enemies. Their use as one-off mechanics is pretty common across modern Mario, and it makes for some pretty memorable levels. Super Mario Bros. Wonder excels at this, using a boatload of new enemies with neat mechanics across a couple of levels each. But how does NSMBU do at that? Well we got a few bangers. Fliprus, Dragoneel, Waddlewing, Grroll, these are some pretty solid additions, and we got some simple variants on older enemies and some returning folks like Sumo Bros or Bony Beetles. Good to see those again, I'll take those for sure. But there's also so many levels that simply...use a NSMBWii concept as a one-off level again. One off Cooligan level in Wii? There's one in U, too. One off Bramball level? That's in both games as well. How about Pokeys, or Huckit Crabs, or Big Wigglers, or Para-Beetles, or King Bills, or Foos, or many different enemies. Ideas in U are presented and used at a near identical rate to Wii, often at the same or similar points in the game.
I can extend this to other level mechanics too. Tilting crystals in an underground setting? That's World 1-2 in both games. Sand Geysers in the desert? Okay, we'll do that again, and also there's a water version now. Lights out desert level with fiery enemies? Sure, let's do that again, I guess a glowing Baby Yoshi makes it distinct...enough. Lights out underwater level? Okay, do that again with the same enemies being used to light the way. Peach's Castle is taken over by Bowser, unique idea for a final world? Alright, let's use the lava gimmicks from the other games and slightly tweak the volcanic debris mechanic and call it a day. You like the Bonecoaster from Wii, that nice one off level? Okay, let's do that one again twice. Lots of the same ideas and concepts from Wii with not too many to call its own.
Now, to give credit to NSMBU, it often does use some of these mechanics more thoroughly than NSMBWii does. I think about the Hammer Pendulums or Cheep Chomps, gimmicks used very briefly in NSMBWii that make for full World 9 levels in NSMBU. The Lifted Lift level in U mixes Wii's ash gimmick and the Magmaws enemy to remix an older idea. Or how about the early Yoshi level in Acorn Plains that also uses the rolling ground mechanic from Wii? There's a nice combination of older ideas.But that's the thing - they're older ideas. U uses world ideas from Wii, a near identical world order from Wii, music from Wii, powers from Wii, enemy and level gimmicks from Wii, all to a wild degree, after Wii already lifted a lot from DS and 2 lifted a lot from Wii and DS just a few months prior. While still a solid game in its own right, and a really good 2D Mario in a vacuum, I find it difficult to separate NSMBU from all of the things that it lifts from its predecessors, more than just the visuals.
In that respects, Super Mario Bros. Wonder is a 180. The same great base physics, but clarified and enhanced with stellar animation work. There are just as many new enemies as there are returning ones, used in several creative ways for some really fun levels, not to mention the Wonder Effects. World tropes remix the familiar in fresh ways, supported by broader world maps packed with main and bonus levels. The power up selection brings back only the core SMB powers but has a robust set of three powers, not to mention a badge system to make the game as easy or as difficult as you want it to be.
Yes, NSMBU is a harder game. Yes, it has a wider boss variety, and more secret exits, and the challenge mode, and more of a raw "challenge", and I understand why that may make it the better game for some. But much of the excitement of that game is dulled for me because it cribs so much of its identity from the rest of its subseries. Not everything lands in Wonder, but from its creative enemies to its many Wonder Effects to its excellently well-rounded power set, it is the breath of fresh air that was sorely needed for this franchise, and that's what makes this the best 2D Mario since the SNES for me.
Don't take this as me going off on you or anything, I just have a lot of thoughts, haha.