Gameplay-wise, this game is very unique: it is pretty much a metroidvania with puzzle and collectathon elements, where each level has different treasures to get, which grant you new abilities or change the structure of other levels, granting you access to new objectives in a non-linear progression (and I was pleasantly surprised that the game never became too confusing, always informing you about the levels to check out whenever something changes in the world map). Unfortunately some sections can become frustrating due to the fact that Wario can't take damage, so you get punished for your mistakes by being sent away from where you're supposed to go. Also, I think the game should have been a bit shorter to complete.
Apart from these two things, the overall experience is very good and I recommend checking it out, I don't think I've ever played anything with a structure similar to this.