Tried it. It's rubbish. It's Mario Kart but worse in every way, maybe except graphics and maybe coins being marginally more useful. Controls are horrible, the most immediate thing I noticed; drifting is bread and butter of this game yet once you enable that, negotiating S curves or steering around obstacles makes you careen into walls since every turn you attempt is a drift or a hop. Turning just feels unresponsive and inconsistent, sometimes turns are easy while other times making sharp turns feels impossible. The railroad makes driving really not satisfactory but it's required especially given the terrible controls. The two laps just make races seem shorter than usual. Idk, there's no stamina but there is an exp/coin cap per day so there's a catch to this. There's no way to stop the item roulette early either. There's also a huge pay to win element to it since the triple item bonus as well as the point assistance for using the correct track preference is pretty overpowered and those with cash to spare will more likely have a better selection to abuse that. I can't imagine online will be any good.
I'm having trouble getting Mario and while this game does have a restart button that erases all your data and lets you restart your fresh rolls from the 20 free rubies, it's tiresome trying to get the character you want. The first roll seems to be Toad and Toadette most of the time, very small chance of super rares like Peachette on first one as report by others. The second roll is generally either Peach or Bowser. If you like those four, great. But I restarted a lot of times, got DK, Dry Bones, Shy Guy, Baby Mario, Baby Peach, Daisy. I've yet to get Diddy or Yoshi but it's probably just rng.
It doesn't help my mood Mario is part of a $20 deal but hell if I lay $20 for a game I don't like.
Graphics are fine for mobile but practically every other aspect of this game sucks.
Overall, game just feels like absolute torture to play especially the abominable lootboxes, and what I've done to Nintendo to deserve a kid's gambling game with some racing in it rather than a proper Mario Kart sequel for Switch, I don't know.