Just booted this up and cleared World 1, including the unlockable 1-S. And... good lord, 1-S. My hands need a break after all that infinite flutter jumping.
I was a little concerned about difficulty tuning going in given Kirby's Epic Yarn (beautiful, sublime to listen to, but with no middle ground between the plodding, forgiving traversal and the extremity of collecting everything), but in the space of nine stages this game has washed away all my doubts about Good-Feel. I'm very impressed with how quickly the game becomes interesting and rewarding to veteran players.
I'm less impressed with the fussiness of spotting and collecting the Miiverse stamp fragments, but thankfully, that's the least consequential unlockable apart from completing stages at full health. I can already see that I'm likely to take the other two collectibles to 100%, if I can.
Obviously I'm still very early in the experience, but I think this is a game that captures many of the same satisfactions as Tropical Freeze for the mid-level player in terms of pacing, inventiveness, and aesthetic pleasure. I don't expect it to touch DKCTF in terms of tightness of design for expert play (Hard Mode and the K-levels made that game, and its accommodations for speed runners are remarkable to watch in action even if you aren't a speed runner yourself), but it's a welcome addition to what is already the most stacked 2D platformer library on any system since the SNES.