Only had a chance to do the initial setup, first tiny bit of adventure mode and a couple of the standalone exercises.
Initial setup is your usual slick Nintendo work.
There is a decent amount of resistance from the ring.
You can tell it your current fitness level and weight. You jog for a bit to calibrate your running style.
The individual exercises show which muscles they target, give you a score rating and have leaderboards to compare against your friends.
First mission of adventure mode is just some jogging on the spot to get you used to the controls.
I don’t think you will need a ton of space. A yoga mat sort of area should be fine.