They'e derivatives of standard Chinese bikes that have been around for a while. All the electrical stuff is fairly standard and reliable as long as you don't leave them out in heavy rain. The bearings in the crank (bottom bracket) are usually pretty poor and can give problems after a short time, but a £10 upgrade to a cartridge type will fix it and last forever.
The 36v one will have more power for better hill-climbing. One other thing to look out for on this type of bike is the control of the pedal assist. Some of the cheaper ones only give maximum power when you pedal, which is not always what you want. I usually advise people to get a bike with at least three levels of pedal assist. you get a little display panel on the handlebars where you adjust it.
The Woosh Gale is very similar to those bikes, and they're cheaper, plus you get the three levels of assist. Their Zephyr is also pretty good, or for serious hill-climbing, their Zephy CD with crank-drive rather than a hub-motor. They support this forum and give exemplary support like all the other trade members linked by the banners a the top and on the right, so in the unlikely event of a problem, you know it will be properly sorted.