Like another reviewer, we had an issue with the back sprocket unscrewing. For us, this happened right at the start. My husband tried to use the bike and couldn't make it around the side of the house before it stopped working for him. Referring to the other review, he checked and figured out that we had the same problem and he was able to make the adjustment necessary to make it work. After a test ride, he pointed out that there were a couple of things which make this kind of bike a bit of a learning curve if you are used to manual bicycles. First, because the wheels are so small, the turning ratio is really short too. Unlike a regular bike, you pretty much turn on a dime, which you need to account for in order to not fall over. Also, if you want to use just the pedals without power boost, you need to turn off the motor. There is no way to just pedal without the bike kicking into the highest speed setting to assist you. These are not deal breakers, just something to be aware of if you haven't ridden this type of bike before. He noted that, in terms of the bike itself, the seat slid down as he was using the bike, so while it started at the right height by the time he returned from his ride he was sitting quite a bit closer to the ground than when he started. We aren't sure why this happened but he's pretty strong and is used to adjusting our regular bike seats, so is familiar with the process, how much force to use, etc. Also, the pedals aren't the highest quality, they have little plastic nubs on one side to help your feet stay on them, but if you are using this for transportation you might want to see if you can trade them out for pedals that are larger and have a better grip (possibly metal teeth). Overall, it's a fun bike and because it folds down it is pretty compact, which makes it a helpful option for dorm or apartment living.