I managed 100 miles during the five days the car was under my care. If we hadn't needed to film it, I'd have managed to use only battery power. As it was...the range extender came into play and, rather incongruously with the rest of the car, sounded like an ice cream truck.
To drive it's very much as you'd expect a city car to be -- especially one made by BMW. The steering is smooth and heavy enough to let you know you're driving something substantial, while light enough not to be a pain around town.
The i3's ethos of all-electric, all the time, is a good one. Though BMW knows there are limitations to it -- you may need a car to take the family on holiday -- and has schemes in place for i3 owners to borrow more suitable cars as and when.