[i played the switch version but i am well versed in the differences and have history with the gamecube version so i can say relatively reliably that the version i played did not change my enjoyment at all]
i dunno... i had a good time for the most part but im seriously torn on how to rate it or how much i enjoyed it. first off there is a lot to praise here: the game is gorgeous, it is immensely charming (maybe the most out of all the 3d marios tbh), the bigger focus on story compared to 64 is a fun direction even if the voice acting is a bit choppy, and the overarching tropical vacation theme is of course fantastic. i also love fludd! fludd is so much fun to use and is a great companion for mario, its serious and pseudo-sterile nature contrasts well with him.
with that out of the way my biggest complaint here and the biggest reason why i dont feel like i can rate it higher is that this is one of the most frustrating games ive ever played.
for one thing its just extremely punishing; the meme that you die for trying to play normally and get mocked with clown honks after is extremely accurate. so many things are punishable by death in this game, from crashing a blooper to not collecting coins in time to doing less than perfect at a minigame. thats compounded with the fact that mario feels uniquely slippery to control in this game in a way that i never felt in 64. there are so many times where i fell off the level because mario kept walking after i stopped holding the stick or where mario did a flip off a platform instead of a jump because i turned around a full second earlier.
again, fludd is fun but also it kind of feels like a bandaid fix so that mario can readjust himself whenever he slips from too much momentum, and whenever the bandaid is ripped off (i.e. levels without fludd) you can really tell the difference. i hear relatively frequently that the secret levels, meaning the levels where fludd is taken from you, are the highlight of the game, but the opposite was absolutely the case for me. they are insufferable.
i also feel like the level design is a bit spotty. some of the worlds are great and fully fleshed out but theres also plenty of levels which were not thought out very well, with thin and uncomfortable platforms that are easy to fall off of, tiny rooms where you have to fight the camera, and occasionally slightly confusing layouts. additionally, a good chunk of shines introduce gimmicks which barely work and which you have to struggle through, my personal least favorite being the awful roller coaster that causes immense motion sickness but there's also the solar panels, the sand bird, the blooper racing, the list goes on.
the last couple worlds end the game on a pretty strong note. noki bay and pianta village are my two favorite worlds and theyre both unlocked last, and pianta village especially gives a great sense of finality. sadly, it then truly ends with corona mountain, one of the worst final levels of any game ever, which manages to both feel like a complete nonsequitor and also an encapsulation of every issue the game has, handily provided for you right before the end.
most 3d platformers have their awkward elements, but i sadly feel like with sunshine they almost outshine the enjoyable core, and it's a real shame because when the game works, it really works! at it's best, this game does indeed feel like an exciting vacation filled with adventure and fun. at it's worst, though, this game feels like a stressful, unplanned, frustrating trip, where everything seems to want to stop you in your quest to have a good time. really difficult score. bordering 3.5 stars, might change it to that in the future if i feel softer to it later.

This game is quite a lot of fun, and I feel like it controls better than some newer mario games in some ways. Something about how the physics in this game work make me feel more at home than what we have now, kind of hard to describe it in a way different than that. I love Isle Delfino and F.L.U.D.D.'s mechanics, they really add a lot to the platforming challenges the game presents you with. I also appreciate the 'secret area' shines, where you have to do platforming without F.L.U.D.D., it almost acts as a test to see if you're relying on F.L.U.D.D. too much. Sure, there are some levels that are less than stellar and blue coins can be a bit tedious to collect, but if you persevere you can get a memorable experience that will make you wish you were visiting Sirena Beach yourself.

Pain.
I'd probably have more fun if I played this game and didn't aim to 100% it. But doing 100% was just... pain.
Pachinko, I feel isn't as bad as everyone says it is. But lilypads... my god. I hate that level with a passion. Had to do the speedrunning trick to get to the island instead of the elaborate bullshit it takes to get to the island with Yoshi Delfino Plaza just to get to the level.
Also felt there wasn't that much diversity in the different levels unlike that seen in 64, Galaxy, Odyssey, etc.

Utterly bizarre in both it's construction and general vibes, but also effortlessly charming and creative. Some of this is Mario goodness at it's very, very best; he controls wonderfully, the FLUDD is gimmicky yes but it's a damn great gimmick, and the levels are consistently unique and play into larger, more interesting narrative ideas at play here. Sunshine isn't a story powerhouse by any means (this is obvious) but there is an attempt here to give each of the levels overarching themes and stories which really works. Makes the world seem alive.

But in the midst of it's gorgeous locales and clever design concepts, there is an unrefined nature to Sunshine that makes it difficult to fully appreciate. Some of it is straight up broken or unfinished, and the difficulty curve is steep to the point of frustration. And the Shines themselves lack the same variety or dopamine hit that 64 gave with it's stars. The further you get in Sunshine, the more it's highs are higher but it's lows get lower, making it a game of contradictions. In spite of that though, it's still absolutely worth playing as an essential puzzle piece of Mario's history.