The software for the game has to be downloaded from the Nintendo eshop and it guides you through connecting the Kart to your Switch and how to setup the 4 cardboard gates. It's a free download of course but can only be used if you own the physical Kart.
Setup was very easy to follow with on screen instructions via the game software and you create your own course given the setup of your living room or whatever space you have this setup on, and the placement of your gates. The Kart does slow down on carpet and gets stuck on shaggy carpet. At first it was very hard to get used to it and I was crashing into everything as our space is about a 10 foot by 8 foot room. Once you get the hang of it though, it is easy to operate and the course you created can be easy once you get used to it.
The gates are made of cardboard and easily move around if you hit them with the Kart, so the game recommends that you anchor the gates with some weight like books. We're already tight on space so we let the gates move around with the crashes into them until I can figure out how to anchor the gates to the ground without books.
Mario's kart and costume can get upgraded as you play through the game, and of course that is virtually (which is disappointing to my kids that it was physically too lol). I haven't played it a lot yet but seems like I can only select to play as Mario. There are different modes you can do with a Grand Prix, Time Trial or a custom mode. While playing the game, it seems cool with the camera and having virtual characters show up and racing them. I frankly would also enjoy watching the Kart too move around the room physically but you can't do that as you have to keep your eyes on the TV screen or Switch screen.
Overall it's quite pricey at $129.99 and I can see the cool factor wearing off but Mario Kart is always a great game regardless. Don't overpay for it and I hope Nintendo keeps ample supply so people don't price gouge.