Very disappointing.
Doubly so since it seems to have the same dilemma of Sticker Star, having what appears to be both wonderful aesthetics and music and stuff. Like seriously, I really wanted to give Sticker Star a chance since it had so many good points, but the gameplay just wasn't up to snuff, with Bowser being the worst offender, having several different phases which each demanded their own very specific Important Thing stickers to be able to defeat (which is compounded by the problem of having to fight Final Kamek right before him who, just like in the other fights with him in the game, turns all your stickers into Sandals stickers during the fight so unless you memorized where you put your important stickers you could very easily use stuff you intended to save for Bowser on accident and even if you avoid that the problem was further compounded by Kamek being able to use an attack that just wiped out an entire row of your stickers, including the ones you need for Bowser and if that happens, which you have no control over at all it's... definitely not a fun experience, to put it lightly. And if they're bringing back the item-checks for bosses like the Kooplaings, I can only imagine Bowser himself will play the same way again which wasn't very fun the first time, so...).
Gah, just so disappointed in this, since aesthetically it just looks so amazing! I really want to give it a chance, like I did Sticker Star. But if the item-check boss mechanic is back, I just can't, because I was burned by that the first time and can't be burned again. Either you have the item, and the bosses are pathetically easy, to the point where they might as well not even be "bosses" because you likely will have an easier time fighting them then you did some enemies (ugh, Sombrero Guys (an enemy in Sticker Star that can double the attack of all other enemies for several turns) in partnership with several other enemies *shudders*), and if you don't, they turn into a living hell.
Those should not be the only two options and the first two Paper Mario games prove it. With those, you had the Badge system, which gave you any number of options, which were all equally viable. Wanted to give Mario a "Dragoon" Jump-based build focused on using Jump-attacks on all kinds of different enemies? Great, works just fine! Want a Hammer Build? Equally viable. High-risk, high-reward "Peril" builds that make Mario do massive damage when in critical health? Works just fine, and is what the speedruns use during most of the games. Make Mario a tank instead with all kinds of HP and be able to endure anything that's thrown at him? Can do. Just invest in as much Atk and make every attack hurt as much as possible? Etc, etc, etc. Sticker Star and from what it appears, Color Splash, have none of that, and instead exist on a binary--either easy-peasy if you have the Important Thing sticker/card you need, or possible but a living hell if you don't.
And I can understand them wanting to differentiate the Paper Mario and Mario & Luigi Series (though between M&L being focused around Bro. Attacks and completely outright dodging enemy attacks, which you can't do in Paper Mario, and Paper Mario having its Badge system and its Partner system focused on characters outside of Mario & Luigi, I felt they had plenty of different, but that's really beside the point). That's all fine, if that's really want they want to do. But then why continue pretending the game is an RPG in that case? That is, why keep the turn-based battle system? That just slows the gameplay down and retains a similarity to the Mario & Luigi games that's completely unnecessary if they really want to differentiate them from one another. If that's really want they want to do, building on the real-time system from Super Paper Mario and using these paint-attacks and stuff in real time would be much more experimental and help them stand apart better.
But yeah, just do disappointing since despite this the game very obviously does have a number of strong points like Sticker Star in the form of stuff like the aesthetics and the music and stuff. Like, it's very obvious that they did make the world look as much like various types of paper and cardboard and stuff, and that's amazing! And that's why I really wish this game and Sticker Star were truly good, so they could shine and be more recognzied for that stuff. But none of that really matters if the gamepaly isn't there to back it up, and I'm just not seeing that here so far, so this will have to be a pass for me again. Just can't make that mistake again, especially since I have much less free cash then I did when I tried Sticker Star and could take risks on this stuff.