Here's my more detailed opinion about Bananza. There's a ton to cover so bear with me but there's so much I want to say about this game.
I want to preface this post by saying that I wouldn't exactly call myself a Donkey Kong fan. I've played and enjoyed the Rare sidescrollers back then except the third one that I skipped but I never was enthralled by them the way some people were. I thought the first one was ok, more of a visual and auditory feast then a really fun game and Diddy's Kong Quest although much better was never near my favorite platformer of that time. Then DK64 happend and I kinda gave up on the Donkey Kong games. I think Rare's collectathon is one of the worst games from one of Nintendo's main historical franchises, I never beat it and the experience kinda soured me on the IP.
All of this to say I have zero nostalgia or emotional attachment to these characters and this world and yet I think Bananza is one of the most unique, admirable and satisfying games I've ever played. I can't even imagine what it must be like for these guys who've been hoping for a new ambitious DK game for all these years. They must be over the moon.
The first thing I want to mention about Bananza is that it's probably the most pleasantly frantic game I've ever experienced. The Nintendo devs talked about their concept for BotW as "multiplicative gameplay" where mechanics interact with eachother to produce interesting or unique scenarios. This is another version of this idea, but cranked up to the max. Where Zelda has relatively slow pacing, Bananza is moving at breakneck speed right from the start. I don't think I've ever seen a game that has so little downtime, and that's because every action that you do has an effect on the environment around you and leads to a continuation of the gameplay loop.
So for example you can punch an enemy that'll get thrown into a wall, explode, create a hole in the cliff and reveal a fossil collectible. Go punch the fossil to grab it and you reveal a tunnel inside the rock. Use your sonar and you see a banana deeper into the mountain. Keep punching your way through solid matter and after getting your main collectible you emerge from the other side where you conveniently get placed in front of a ruin where a challenge room awaits you. Rinse and repeat for hours on end, and this never gets old.
Bananza's level design is the best I've seen in a 3D platformer and at this point I don't see how it could get surpassed except by the next game from EPD Tokyo. I've already said that the designers managed to cram all these micro exploration loops everywhere in their stages but it doesn't stop here, the levels at large are designed to be interconnected and to naturally return you to your starting point in the main landmark of the layer once you begin exploring for side objectives. You unlock a variety of shortcuts, either by dropping ropes from higher layers or by paying money to build bridges or barrels. It's trite to even make this comparison at this point but it legitimately feels like Fromsoft level design, condensed and curated for an exploration based 3D platformer.
The levels being organized in sublayers also make use of verticality for some fun navigation puzzles where you have to find an entrance in an upper layer to a place inaccessible from a lower layer. This immediately evokes Tears of the Kingdom, and this isn't the only inspiration Bananza takes from other Nintendo games. In fact Bananza feels like a compilation of the major Nintendo first party titles released these past ten years or so.
From modern Zelda it takes the aforementioned approach to verticality but also environmental manipulation and elemental interactions opening up plenty of creative ways to reach any given objective as well as more minor nods like the additional yellow hearts after sleeping in a refuge or an obvious reference to one of the main regions and divine beasts in BotW. The surprising focus on aiming and light TPS gameplay (it becomes more and more of a feature the deeper you get into the game), Pauline's musical powers and popstar-like performances and an overall very gaudy, strange and sometimes slightly unsettling visual design immediately evokes Splatoon. Of course the most obvious comparison will be with Odyssey given it's the same devs behind both games and they share a lot of common in terms of objectives, basic level structures and progression.
Even so I can confidently say that Bananza surpasses Odyssey in pretty much every way. I've already talked about level design but let me get back to it a bit because it'll highlight the difference between the two games. It's not simply that Bananza has at the same time more chaotic and more complex worlds that still manage to be easier to read and more satisfying to navigate, with less downtime and empty space (the levels are both massive and dense: none of these things should work together and yet they do), but they also introduce more unique mechanics than Odyssey's kingdoms. Starting from early midgame you'll be met with four to five new platforming mechanics, physics interactions or environmental hazards in every new main layer. This goes a long way to avoid Odyssey's main issue which was the repetitive and pedestrian nature of its interactions.
Another way Bananza manages to stay far more engaging all the way through is by introducing new abilities through the animal transformations, and this allows us to segway into another one of Bananza's many successes, DK's movement.
I've already spent far too long waxing lyrical about this game's merits but I think I could write the exact same amount of praise for the core movement in Bananza. I'll spare you though and try to be concise. Bananza has the best movement in any 3D platformer I've ever played. In fact it has the best movement in any 3D game I've ever played period. The number of moves you can pull off, the nuances of the mechanics, the way they can be combined with eachother to create new ways to move through the levels, their interactions with all the platforming mechanics introduced throughout the game, the fluidity of all the various cancels and the phenomenal feedback of every action, no other game comes remotely close to the depth and expressiveness of Bananza's movement. It makes Mario look stiff and restrictive in comparison. I won't talk about other 3D platformers because I don't want to be insulting. I honestly have no idea how you top that.
I guess I'll have to talk about the game's flaws because obviously it has some but as far as I'm concerned they're more minor annoyances than anything. I've seen a common sentiment being expressed about the game being too easy. It's definitely not as challenging as the 2D DK sidescrollers, not even close, but it's also not as free as some would claim. I haven't done any postgame content yet but the mid to endgame get some pretty noticeable difficulty spikes and I've died quite a few times throughout the playthrough. Definitely harder than most 3D Marios and of course harder than Kirby and the Forgotten Land, still it's true that if you're looking for the Dark Souls of Crash Bandicoot you won't get it here.
Similarly I've seen people complain about the music and I disagree here as well, I find the OST to be of very high quality. All of the Bananza transformations theme songs are fantastic earworms, the remixes of David Wise's classics are perfect and the EPD composers even managed to be the only ones to successfully imitate Wise's signature style to create an original track that is as good as anything from the master himself. You'll know what I'm talking about when you get there. It doesn't stop here either as another theme is reminiscent of Okabe's legendary work on the Nier series.
Anyway let's finish this with the performance issues and even if they do exist their prevalence is vastly exaggerated. They're really only a problem during a handful of specific boss fights where the framerate indeed shits the bed which is a shame as the fights themselves are the best in the game but other than that they're a non factor. In fact my only main gripe with the game is with the gyro aiming and how it tends to go apeshit randomly, completely desyncing and moving by itself up and down which can be a pretty big problem in the more tense combat and platforming scenarios requiring you to throw a piece of material quickly and precisely.
With this rambling wall of text coming to its end it's time to come back to my introduction and amend what I said here. I stated that I was never a fan of Donkey Kong but it's not entirely true, I started becoming a fan after playing Tropical Freeze more than a decade ago. It's not that I became enamored with the character all of a sudden, but I simply had to admit that this big goofy ape now had the best 2D platformer and one of the best Nintendo first party titles under his name. Today I can safely say the same is true for Donkey Kong Bananza. The Donkey Kong series now holds the privilege of having the best 2D sidecrolling precision platformer of all time and the best 3D collectathon expressive platformer of all time.