You're gonna need a fender or you'll end up with a dark stain on all of your clothes... Remember the rooster tail that your old BMX would throw up?

Haha, we don't sell them but the seat post allows for attaching of the conventional fenders.

While going downhill, does this know it, or start breaking. If going downhill, does this take advantage and start generating energy. Another option could be to design its backpack.

I just don't get it. Bicycles work great, don't need charged (think fruit fuel), are MUCH faster, weigh less, have unlimited range, and you can get a pretty damn sweet bike for less than $1k, this just seems silly, looks silly and is plain lazy...

Get this, thewaldron. If you work in a office, you need to be at least semi-fresh and need the space for your bike as well, right? And what if you need to (can/want) go to a party afterwards. Where are you gona store your bike if it's in a dark neighborhood? These devices will offer a modern alternative to cars and motorcycles and their triumph is their compactness.
P.s. - I cycle as well.))

Is it possible to attach a small motor and battery pack to run at low speed?.

I love these things - but, I always laugh when I see it because it reminds me of the guy from the 'BC' cartoons... :o)

Get what, Renārs Grebežs?
You really expect to drag this into somebody else's home for a party, or expect it to be welcome in a bar or a store? You know what's even more compact? Folding electric stand-up scooters. Yet even though those can be bought for a lot less than this, and you look much less dumb on one, those haven't set the world on fire.
I'm all for green transportation. I've bought, tried and sold more gadgets than probably everyone else here. Where 99.999% of the population is concerned, this will always be a toy.

But it is cool! Looks a little scary, though. And how do you get down from it in a hurry?

I'm also all for green transportation. But the SBU V3 looks a little heavy with the seat on it. I read it weights around 13 Kg, with an autonomy of 12 Km. I think the best alternative of Self Balancing Unicycle is the moCycl One, their SBU weights 9 Kg and has 20 Km autonomy.