I got to demo ride a Zero "S" Thursday at a dealership in Eustis, FL. It was a pretty good ride too, we went about 20 miles through town and out on the highway, right around what passes for "rush hour."
It's a damn impressive bike. It snaps right off the line, accelerates like an average Ninja 500 would, and runs right up to 80 mph with more available. The bike feels very light, but not in a skittish way; you can toss it into corners and make it go wherever you want. The regenerative braking is neat as hell...the sounds it makes (and doesn't make) are cool, it's a complete package. IMO, Zero has a highly capable motorcycle that happens to be electric.
BUT...and this is not suprising I guess, it is EXPENSIVE. I had the dealer write up a sales order for the "9," which is the high-capacity, high-speed version. With tax, tag, blah, blah, and blah, it prices out the same as a brand-new Concours 14. Ahem. Well.
BUT...another but...my uncle was in Engineering school when the first HP pocket calculators came out. He paid $650 for one and was damn glad to get it. Two years later they were selling a better version for under $200. The same will happen with E-Bikes.
After riding the new ZX-1400 and the Zero S on the same day, I've come to the conclusion that gas-engined bikes are at their technical apogee. Horsepower has become almost irrelevant; they can produce more than enough in a small enough package that the real differentiator between G-Bikes now is their electronics packages (FI, TC, ABS, etc.). E-Bikes, on the other hand, are in exactly the opposite position in their life cycle; the early prototypes are done now, usable production versions are available (albeit at a price) and we're going to see some truly amazing products in the next few years.
I think the E-Bikes are so good, so compelling on their own merits, that no goverment subsidies or rationales like "saving the planet" will be needed to sell them. People are going to want them because they'll haul ass and generally be as much or more fun to own and ride than G-Bikes. This little dealership in Eustis has already sold 4 9's, 3 6's, and while I was there, sold one of the previous-gen bikes off the sales floor.