I love GiT - that being said I do believe it to be the weakest main WarioWare instalment. Some microgames are pretty tough to figure out first time (Mona's boss is an example) which, although it only applies to a small amount of them, is a major detriment to a WW game. Gold had this issue too, but to a much lesser degree. The characters are also pretty imbalanced - which wouldn't be a problem if it weren't for how imbalanced they are. Master Mantis quickly renders Young Cricket irrelevant, same with Jimmy T. and Crygor respectively, and Orbulon is introduced way too early. Being forced to choose multiple characters was a great design choice, but honestly I wish the post-game "all" mode was forced instead since then the imbalance would be countered out by RNG
The character-swapping is fine and luckily isn't too intrusive. I see it less as a homogenised (I love to use that word) gameplay style and more just a new control gimmick like touching, twisting or smoothly moving
I also think the aesthetic (menus especially) and soundtrack lacks the edge DIY and prior had - I love the Gold and onwards WW art style but not the menu aesthetic and soundtracks which lean a little too "wacky" IMO. That being said, the callbacks are brilliant. Even though I complained earlier about Mona's monkey getting a cutesified redesign, Mona's animal buddies coming back at all is miraculous - in fact I'd say it's a blessing Wario's friends still appear at all. Nintendo could've easily swapped them out for Nabbit, King Bob-Omb, and Kamek but didn't, and in the age of the Mario Mandate we should be grateful for what we can keep.
I really dislike how Dribble & Spitz' stage was handled, it's kinda been a problem since DIY Showcase, I much prefer the more soothing vibe of prior D&S stages that leaned more into Dribble's "gentle giant" side than "speed freak" side. Penny's stage did fill that D&S niche decenty though. If it was rainy night (which would've made sense in the context of the story) it would've really scratched that itch even if the song is more pop than any D&S song.
I like how Wario is characterised here - he's greedy, lazy, and easy to anger but never enters true villain territory by choice - in fact, he might be a little too nice! other than refusing to go back in the game to rescue Red and Master Mantis with his employees, he doesn't really do anything morally questionable - just say stuff that's morally questionable. Wario not paying his employees isn't even brought up! (it is alluded to though) Wario (at least in Ware) is a character who's glaring flaws really enhance other characters' relationships to him - when he does something scummy they put him in his place of course, but they ultimately respect and care for him, which I find really cute - especially in the context of Wario's prior history which creates a sort of unintended 30-year-long redemption arc - while pure-good Wario is fine IMO, if you remove or, in GiT's case, downplay his greed and anger you're just left with "funny Mario" instead of "bad Mario". That being said, while most of this paragraph has been critical, I am happy with how Wario is portrayed here - I'd rather him lean too good than lean too bad. (Subspace, anyone?) Wario's an anti-hero and anti-heroes are all about balance, but Wario is a very different type of anti-hero who generally isn't explored much in gaming, less Punisher and more Mr. Krabs, so I can understand why writing him may be a struggle.
The minecart stages were quite disappointing. I would've much prefered Jimmy T. variants or his family. That being said, I like making the variety towers part of the main story, even if it's a little redundant with the mine carts.
Pyoro as the final boss was a great twist, I've always wanted to see him get more roles. I have to admit that it feels like the Great Developer was supposed to be Waluigi but the mandate squashed that - the way he's revealed really comes off as "OH MY GOD IT'S GONNA BE WALUIGI" as his ears are the only thing you can see other than hair, but it just turns out to be a Wario clone.
Buddah Wario. Buddah Wario.
GiT isn't a disappointment, in fact it's a great time, but it has some flaws future WarioWare games should squash fast, and is a casuality of the Mario Mandate in subtle ways.