His original fatbike was very cheap and many people were sceptical about whether he would deliver, but most of the concerns weren't realised. There were the normal quality issues you could expect with any new start like that, but it seems that most got what they paid for. He's now followed up with more models that are still built down to a price, but offer more than the original one. Basically, for that price, they're not bad. They're easy to fix and the standard parts are available from lots of suppliers (mainly Chinese).
I've tried that 48v motor in another fat bike, and it went pretty well. I have a reservation about the gearing on that bike. With 7 speed, it's most likely freewheel gears, which probably means 14T top gear, but the chainwheel doesn't look big enough, so the gearing might be too low for the speed of the motor. If it is like that, it wouldn't cost much to upgrade it to faster gearing.