I've driven one!
Having driven the Model S, I'm quite impressed. The massive touch panel for a dashboard is well designed and easily configurable - it also screams "you're in the future". You can select whether the car 'creeps' or not when you take the foot off the brake. You can also adjust ride height and a whole host of other options while driving. It's worth noting that these things can be adjusted using controls by the wheel as well - with feedback from the instrument panel to avoid too much distraction.
Putting the foot down is great fun - but it'll really limit the range. Also - good bye to a lot of braking in the city. The car will start recovering kinetic energy as soon as you take your foot off the accelerator. This is a bit odd at first but you get used to it (also configurable)!
The only thing I didn't like was the badly placed inner handles on the doors and lack of grab handles on the roof. Not to suggest the driver will be throwing the car too much round corners but it's nice to hold on in comfort.
I'll be interested to see where charging stations will be as it'll dictate how practical I reckon buying one would be. At the moment I'd say it's certainly a luxury and it's not green if it's powered by coal power when plugging in at home. Good job Tesla on leading the way, I look forward to seeing how this develops. Also look forward to getting a go in a BMW i3.