What a mixed bag. This game has so many problem gameplaywise, which in a fast paced game like this almost always leads to unfair deaths. Examples include the homing dash being way less reliable to actually hit your target, and the landing on rails in stages like Rail Canyon can be a shot in the dark at times, not helped by the fact that it often lets you move your character in the air in sections where you really should not be able to. Other negatives include annoying bosses and the fact that stages reuse a lot of their own parts and gimmicks in the same stage, in the exact same way, making the stages last way longer compared to other games while it feels like you are actually playing the same sections twice. THAT SAID, once I got used to the jank after the first story, at which point I hated the game, it becomes a lot more fun when replaying it in the other stories because you know what to watch out for. Doesn't excuse the jank, but there is a fun game here. The 4 different stories should have had bigger differences between them to justify their existence, though, a major downgrade from the stories in Adventure and it feels like padding here. Oh, and the special stages are pure garbage.
Some extra positives are that the music, stage themes and the upgrade mechanic for the characters are all really great.

A pretty okay game all things considered, though playing it all the way through does sour the experience.

To start with, having four campaigns is not a terrible idea if the gameplay styles were more different. But they're not. They play mostly the same with the exception of the special moves of the speed characters, and some moves from the power characters. I never noticed a difference in any of the fly characters, other than Charmy's ability to open those flowers. But that doesn't really count, now does it?

The level design itself is actually quite good. I like levels from across the entire game in general. I think the bigger issue is how the game feels to control. I don't think I'm the only person to feel this way, but this game feels slippery compared to the previous two adventure games. The flying characters feel very awkward throughout all campaigns, and the power characters feel awkward with stop and start movements that feel kind of jittery. The homing attack works great, but I feel like it's really missing the "oomf" that it has in the Adventure games.

It also cannot be overstated how much worse this game feels when you have to play through it four times in a row. If it felt great to control I genuinely believe that there would be no issue playing through the campaign 4 times, because the levels themselves are really engaging. But the controls really start to get on your nerves after a while.

In short, this is a game hampered by having four separate campaigns, and its somewhat awkward controls. The level design itself is great, and the soundtrack is great, but it's hard to enjoy due to its repetition.