The hardest part is putting the straps on the segway Ninebot S motor. It is so much fun, my grandchildren love it. It's great, a little slow but great.

My son absolutely loves it. He's 8. But also it's great as an adult too. And even with a regular sized grown person riding, it won't slow the machine down.

Had a Ninebot S for a few years and never really rode it nor took the time to learn it. Keeping an eye on this and saw a good flash sale so quickly ordered it. Assembly was pretty straight forward with only needing to put on the seat and the armrests; and they supply the tool. You need to take the knee bar off the Ninebot S before you use it with the Mecha kit, and do note they give you a specialized toolset to do it in a baggie, and they instructions to use it are later on in the instruction booklet; I learned the hard way, hehe.

The thing is slooww, at first. You see, Segway wants you to complete certain exercises on the app and ride the Mecha kit for a certain amount of distance before they unlock the faster speeds. Once you get the Sports mode unlocked (through the app), the fun really starts to happen and now you feel like you are getting somewhere, faster.
I would be a little weary of Sport mode for younger kids or for the squeamish because looks like you can flip this thing if you lose control or try to turn too fast. Just make sure to not turn on faster modes until ready.
My only real complaint is the super low profile of this thing, so even going onto a driveway can get this stuck because of the very low front end. I have to go up at an angle and with speed to scrape my way though. :)

The back casters are plastic and are adequate, I was thinking of changing them out but if I put even slightly bigger casters, then that will lower the front end even more. :(

Overall, I recommend this as it is still very fun and with the faster speeds you will be able to "turn" a little faster because at the slower speeds, it is "uugghh" torture. You find ways to make it work better as you try different things. And of course, always check for the latest firmwares as they add goodies and updates.

For those that are wanting to know, yes, it is compatible with the Segway Mini Pro. I purchased the Mechanic Kit and hooked it up to my Segway Mini Pro I purchased in 2017. Works great! The seat leans a little too far back but I'm 6 feet tall and 295 pounds. Even at my size, works great! You will need to download the newer app by scanning the QR code in the book. Also, make sure your tires are properly aired up before attaching the Mech Kit.

After I called Amazon for support, I realized that it was not compatible with my Segway, after pairing it to my newest Segway, which is just the S model. It works absolutely great, and I love riding this more than the kids.