I enjoyed the original New Super Mario Bros. because there hadn't been a new 2D Mario in awhile and frankly I just kind of unironically like bland 2D platformers (I really like Giana Sisters DS). After that, I pretty much fell off every sequel- partially because the emphasis on co-op made levels just feel too big in single player, and beyond that they had just become too bland. There was no sense of place or journey to it- things that Super Mario Bros. 3 and Super Mario World had excelled at with wild new things in every world. Even 3d Marios like 3d World/Land fell into similar issues, often not even caring enough to stick to a level theme within a world. Nintendo's own lower profile platformers like Donkey Kong Country Returns put them to shame in production values too, with details like having platforms actually connect to things. Super Mario Bros. Wonder is seemingly an attempt to correct this longstanding issue, proudly showing off the game existing in a new kingdom with new Wonder Flower collectables that suddenly change levels in dramatic ways- living pipes, stampeding rhinoes demolishing the stage, and more! But does it actually succeed?
The wonder flower system itself is certainly the highlight. Tons of platformers have stages with gameplay-altering gimmicks or straight up minigames that deviate from the core platforming. What Super Mario Bros. Wonder does is set up suspense (at some point there will always be a wonder flower) and payoff (wow this wonder flower turned the game into an overhead game). Time and time again I found myself surprised by getting into the groove of a level before remembering: "oh man I wonder what the flower is gonna do here". For something so simple, it works surprisingly well.
What's less effective are the wonder effects themselves. While there are plenty of good ones, there are just as many whatever ones. For as hard as the game wants you to think it's crazy and wild, it's actually pretty conservative with the range on display. Worse, the game recycles a lot of them. I'm not against the recycling itself, if anything I find it disappointing when a game lets a mechanic go underused, but it often fails to escalate the effect when it does. Yeah, turning into a blob that sticks to walls is cool, but you aren't making me do anything new with it the fourth time you've given it to me so now it just feels like a letdown.
On the aesthetic side, character animations have undergone a dramatic improvement. They actually have personality now- Mario breaks out into the Mario 3 running pose, elephants get stuck in pipes, hands stick out to catch wayward hats, etc. Really the level of detail is phenomenal: characters and enemies track each other with their eyes, change facial expression when near enemies, enemies bump into each other in cute ways, etc. It's a dramatic improvement from the stilted New Super Mario Bros. games, and it adds a ton. Less successful is the world which sticks to the New Super Mario Bros. style of squeaky plasticy clean dirt and grass. It has a soulless corporate CG vibe to it, but there are enough added details and layers to things that it took awhile to really set in. I found myself simultaneously impressed and disgusted by the game's visuals in a way few games manage.
The other big success of the game is how it approaches difficulty. Recent Mario platformers have fallen into making the main levels dead easy and then slapping on a post-game with hard as nails levels. I absolutely despise this approach because straight-line difficulty curves are boring- they don't create stress with difficult sections and then release with easier sections. Instead they feel like having two games that aren't quite right: a boring easy game, and then a game of unrelenting difficulty. Super Mario Bros. Wonder fixes this by mixing those former post-game levels throughout the entire game. Even better, it hides those harder stages making thorough exploration feel rewarding (which itself is impressive- often times exploration just rewards you with making the game easier which is backwards, people who are invested enough to explore are probably seeking an escalation). While I do wish they had more hard levels overall, the mix was fantastic- after dealing with the hard stages, the easy stages felt like an enjoyable break.
There are few more details I can touch on briefly. They shake up the overworld formula a tad which was nice, but rarely impressed (a free roaming desert full of secrets was the highlight). Badges let you augment your move set with things like Luigi's jump or adding a simple grappling hook, which is nice but underwhelming by virtue of being optional and numerous (I opted for the secret alert badge because frankly the game is overloaded with worthless secrets that just give you meaningless coins, so having something tell me whether a secret was worth my time was nice even if I'd usually hate such an item). And for some reason they injected a bunch of story into each world and it's all bland and has way too many text boxes. Oh, and they added talking flowers throughout the levels that react to how you're playing. I liked them. Sometimes they're even funny. Mostly they're just tutorially/hinty. Kind of reminded me of early CD games scrambling to find uses for the tech. Charming.
So overall Super Mario Bros. Wonder is a good game, but also faintly disappointing. It's basically what I wanted from the New Super Mario Bros. sequels to begin with: well-crafted generic platformers. Yet the way it promises to go crazy and wild while only occasionally going hard, on top of the years of bland games in the series makes it feel a bit like a broken promise. Should you play it? Yeah, if you like 2D platformers.