I have a 1 week old 800Li. What do you want to know?
The most obvious advantage of Optibike's design over hub motors is reducing unsprung mass and keeping the center of gravity low, producing a bike with great handling on and off road. It also offers good efficiency on ridiculous climbs. But for me, the deciding factor was that it is engineered as a complete system. For example, the battery management will yield years of extra useful life for the lithium ion packs, compared to hobbyist charging systems. The motor is oil cooled. The controller senses battery and motor temperature, preventing overheating during both use and charging. I am impressed by their engineering, and I am not an easy guy to impress.
If cerewa and Snowsurfer are trying to say the Optibike is overpriced by comparing it with motorcycles, they are right, but that's what you'll have to pay to be an early adopter. In other respects, the comparison is silly. Blippo is correct: sane buyers of the 800Li can afford it and a motorcycle. For my part, I don't want a motorcycle, but there are days when I need some help if I am going to ride a bike.