This game had a lot to live up to being the 1st Mario game not to be NSMB in almost 2 decades, and it delivers. The wonder mechanic is super fun to interact with and keeps the gameplay diverse and interesting, Mario controls like a dream, it's its own unique game while still having all the components that make a main series 2D Mario game feel like a Mario game.
I haven't played every main series 2D Mario, but I don't think it's a stretch to say this game probably had the best controls of any of them. I've never had too much of a problem with controlling Mario in the other games but I'm so used to him being more floaty and slippery. The controls may have even been too good for this game, but we'll touch on that later. But it was super fun to be Mario and being able to tare through levels when replaying them is fun as well.
The powerups were a joy to play with. Nothing to write home about, except perhaps the elephant simply for the visual aspect of it. I feel like I would've gotten a lot more adept at using them if there had been more content in the game (worth noting that I still have yet to complete 100% at time of writing). The Fire Flower kind of felt out of place here, I think it was probably only included because it's been a series staple since the beginning, and it would be odd not to have it.
The Wonder Flower, on the other hand, was a very cool mechanic. The concept of an "optional" challenge that changes how the game is played is such a cool idea. The wonder effects were all visually interesting and appealing to look at. It really felt like something wild was going on. I pretty much liked every wonder mechanic, it was nice that they were contained to parts of the levels specifically designed with the mechanic in mind as well. Some of them made the game easier, some of them made the game more challenging. All in all, just a really awesome thing to play with. I liked finding the flowers in each level, and I loved the variety of effects that were possible (never got stale) as well. Banger mechanic.
The levels themselves were pretty short and straight forward, nothing wrong with that, especially because I think the level design is quite good. However, the game felt almost too easy to beat. I may have trouble with 100%, but to go back to my earlier comment about the controls being "too good": a lot of the levels feel like they were built for a slipperier/floatier Mario. I'm aware this is mainly a matter of personal preference, but I feel like the platforming could have been made a little tighter and the controls left the same. I haven't played that many Mario games, but I've never breezed through one so quickly either.
I was not, by any stretch of the imagination, good at the game, but even still I didn't really feel very challenged by any particular level. Even the ones where I died a lot it just felt more like I was being an idiot than anything else.
That being said, some the 5★ difficulty levels I've already played in the special world are kind of like, the perfect difficulty for me. Makes me wish the game had more levels like them, simply because I'm having so much fun playing them. I think it would've been cool to have some levels around that difficulty sprinkled into some of the main worlds. Given how bad I am at the game, I can only imagine what a cakewalk every other level must be for someone who's good at Mario. This may not be a grievance for everyone, just something that I noticed. Hopefully we can see more levels like those special world ones in SMM3.
Overall, I think it was a great game, and worth the $60 or however much it is to play. It's a great entry into the mainline Mario games because it still absolutely feels like Mario, but has enough new content to still be a fresh new game. I'm glad to see Nintendo finally breaking away from releasing the same game for decades, and I feel like the series is moving in a good direction. My only issue with the game is that I feel like my initial run through was pretty short, despite the fact that I was not in any hurry to beat it. There are very few genuinely challenging levels (though there are a handful of annoying ones). In the end, I had fun. So in that respect, it's exactly what it needed to be.