I've had a UM36 for almost a year now, very much enjoyed riding it, waited about 3 months after putting a deposit on one because I wanted the lithium battery version, which turned out the original lithium-polymer batteries had bad problems and a significant amount were recalled because the battery manufacturer came clean and said they couldn't reliably get 12Ah into that pack, so for most of the time I owned the bike I was using a prototype lithium-ion battery which didn't get me very far and had to take the charger with me most times - but I could still use my bike which was the important thing.
The good news on their battery front is they've sorted it, now they're offering 9Ah Panasonic li-ion batteries which I was given a few months ago and it's not let me down once, in fact I haven't been on any journeys long enough to completely drain it - but I will when the weather gets nicer.
Customer service wasn't so great, several times when calling the company direct I was promised callbacks which never happened, though through emailing I did get direct help from the founder of the company who is a nice guy and has a passion for the bikes & business as he enjoyed showing me the new innovations at their main warehouse in Cheltenham when sorting out my battery problems, plus I also enjoyed talking to him and seeing the place and protoypes etc.
Their new range of UM36's the UM36X is matt black and they do a larger frame which I could have done with as I had to go and buy the longest seatpost possible for my UM36 to be comfortable, along with buying an adjustable stem (which the new UM36X also now has).
But the biggest loss of their new bike is the throttle, whilst I find it's a bit cranky to use I really like having it there - the first half of the twist does nothing, the 2nd half of the twist makes the bike go (variable speed) but only after cutting the motor when you're pedalling and waiting 3 seconds, on top of all that the throttle only gives you 10mph max
Despite the problems I've had with the battery and customer services, I ride it literally daily as I have no car and I love riding it, if I spend a day without going out on it then something doesn't feel right.