Joules have been around for a few years but your guarantee is with the vendor. If you don't buy directly from Joules then there is less certainty, you may need to clarify the terms of guarantee with the vendor. The electrical side is fairly standard, the bike can be fixed by most trade members of the forum. If you like the look of the bike then go for it, the risk is small.
When you get the bike, check the motor manufacturing date, it is usually printed just before the motor serial number. It will give you a pretty good idea when the bike was made and imported, hence the life expectancy of the battery and the likelihood of the vendor continuing support. More recent is better.