I bought two of these for my kids recently. They are very cool and resemble the mini bikes I remember seeing growing up as a kid myself. Sadly, my parents never allowed me to have one, so now I'm reliving that experience through my kiddos. There's a lot of minibikes in the market to choose from but I believe these are by far the best bang for the buck hands down, which makes modding them even more enjoyable because you don't have a lot of money tied up in them.
A couple things you should know. #1 Coleman doesn't do an adequate job of packing these and there's literally no protective covering on the frame, fenders and other hard parts. That means, aside from the use of cardboard which does protect some components, there's a good chance you may have some damaged parts when you unpack the bike. I found metal on metal contact with some of the parts only being zip tied to the frame and nothing in between to prevent rubbing of metal parts. Some hard parts like the chain guard, fenders and forks/handlebar assembly were mangled and simply need to be replaced.
#2 if you're buying from an online retailer like Amazon, Walmart.com, etc you should expect your box to arrive damaged. In my case, the handlebars had punctured the box and some parts were missing...apparently fallen out during shipping. Fed/Ex and UPS is absolutely terrible when it comes to handling these items. I saw how mine came off the truck and one of the boxes that the mini bikes came in was laying on its side on top of other smaller boxes, probably crushing them. Morons!
#3 Like all the reviews have said, you should expect damaged parts. If you get lucky and yours arrives unscathed, consider yourself lucky. That said, Coleman has good customer service and they try their best to replace any damaged parts. Be advised though, the parts may be out of stock and it could take some time for them to arrive. It's been 3 weeks and my parts are still on back order. They are coming from China and at this point there's no telling how long it might take.
Now...with all of the above factors taken in to account, I still think these mini bikes are the best deal going and if you get one that's not damaged, that's even better. The bikes are manufactured for Coleman by Hisun and assembled in McKinney, Texas. The build quality seems to be decent, but not of the higher quality you'd expect from say, a Taco mini bike. The welds on these Hisun's are acceptable, but for my liking they leave a bit to be desired. Not real clean looking, but you then again, you can't buy a completed Taco for $350 either. Most people probably wouldn't think twice about it. You get what you pay for.
The strong point about these mini bikes are in my opinion, the motor. I had never heard of Hisun beforehand and thought maybe they came with a smaller Lifan or Predator motor. Nope! Turns out Hisun manufacturers their own engines and it's a good little motor. Compared to the Lifan on the Monster Moto, the nearest competitor to the Coleman I would say I like the Hisun motor best. The placement of the choke, throttle linkage, gas shut off are easily accessible and well thought out. They also start on the first pull usually. I weigh 170 and live on 2 acres of rural hilly land. To my surprise, these little bikes can really move when I'm not trying to tackle the hills. You can only expect so much from 3HP without the benefit of a jackshaft or CVT. Given those conditions, they do very well.
One other thing to consider, there seems to be an abundance of aftermarket parts available. Plenty of people here have added jackshaft kits, CVT's, headers, larger air cleaners, and added larger jets to their carbs. I haven't seen those kits for the Monster Moto's, so it it seems like most people opt for an engine swap to a 212cc Predator motor, which is always an option on the Coleman also. TONS of aftermarket goodies for the Predator 212.
So that's the gist of it. If you're looking for the best value and are willing to deal with some hassle and inconvenience of parts arriving damaged and can make repairs yourself, I would not hesitate in buying a Coleman CT100U.