We recently purchased this go kart for our daughter on her 9th Birthday. It turned out great, and she loved it. It was fairly easy to assemble, probably took me about 45 mins to put it together. Make sure you connect the wiring under the rear cabinet before trying to charge. Ensure that you charge it overnight before its first use. It charges relatively quickly. The go kart itself has a metal frame, plastic front tires and rubber rear tires. The rear tires make it very easy to drift on asphalt. Our daughter drives it all over our front yard including our grass and it doesnt seem to have any issues making it through the grass. It sort of sounds like a Tesla with the electric humming sound. We chose the pink color, and now our twin sons each want on in their own color as well. WE havent looked into upgrading the battery pack for more speed yet, because at high speed it seems to have ample power for our 9 year old.  We havent fully tested out the battery length, but she drives it on full speed for about an hour almost everyday since she got it. 

Couple things to further note: 

My Daughter is quite tall for her age, smaller children may have difficulty reaching pedal

It's fast - I have upgraded 18V drill batteries in my boys Ride ons and this Kart is much faster.

Having two speed functions and reverse is great.  

Drifting is a ton of fun, my daughter really loves peeling out and doing donuts. 

I will update this post as time passes, we have owned it for less than a month now, but so far so GREAT!