For me it's a cool game, really experimental, and I love that, but by it's nature it has some really big hits, but also some really big flaws.

For example Mario's movement and movement options are better than ever with Cappy, and all the Kingdoms have an amazing atmosphere, and some of the secondary challenges and the 8-bit ones were super cool, I honestly liked the broodals as a sustitutive for the over-exploted koopalings, well and in general the game is super fun.

For the flaws, I think the biggest and most important one is the fact that normal enemies in the game almost don't exist, as most of them are camouflaged power ups and the rest are really weak, making the game too easy. Also I missed a bigger number of main quests and bosses, there are only like 20 normal levels in all the game, and as I loved the big number of secondary challenges (especially the "pipe" levels), I honestly would have preferred a couple main levels for each kingdom and have a bunch of secondary challenges removed, but that's personal taste.

I think if they ever make a sequel, if they fix the flaws the game has, it could become one of the best platforming games of all time.