A Zero definitely does feel tiny, yet not cramped. And I am a small guy myself. For my last bike, I chose the BMW F800R because of it's qualities as a commuter; narrow, light weight, low seat height, plenty of torque, and amazing fuel economy! The Zero S is just so much better at all those qualities, and is also the same naked standard form factor that I love! There's also the fact that I never think about my bike stalling because there's a chance I fumble the clutch. This is great when I filter up to the red lights, and want to just launch away from all the cars without a moment's worry when that light turns green.
I find it disheartening when people compare a Zero to other motorcycles based on its range, it's charge time, and its cost (those are the three things I keep getting asked about). This has been my primary mode of transportation for the past couple weeks. Maybe I'm a different kind of rider, but when I'm on this thing I'm only thinking about how much better this feels than other motorcycles I've ridden, and how much easier this has made my life. I don't care if I can't do more than 80 miles of highway riding. I wouldn't want to do that on my F800R anyway as the vibrations of the handlebars make my hands irritably numb.