I have had my Model S for a week and a half, and just drove out of town in an all-electric vehicle for the first time. It was cold, rainy, and night, so between lights, heater, radio, and the extra drag from the rain I averaged a bit under 400 Wh/mi. This was with cruise set on 75mph most of the way, and there was moderate elevation change (Atlanta to Chattanooga; Appalachian foothills). I started off with a max-range charge (so in case the hotel I was staying at had a problem with their chargers and I was unable to charge anywhere, I would be able to make it back home (though slowly), and it showed 271 rated miles. I drove 111mi, and it showed 130 rated miles when I stopped, so I used slightly over half of the battery capacity. So, I think I would get about 210mi under similar conditions if I drove until empty. That is pretty much in-line with my expectations before hand.
The charger at the hotel is Blink, and the hotel web site said it was complimentary to guests. However, the guy on duty in the middle of the night didn't know anything about that (in fact, he said it was the first time anyone had asked about them in the 2 years they had been there). So, I am charging as a Blink guest at $2/hr -- even if I can't get it straightened out with the hotel, it will take about 7 hours to recharge and cost me $14, less than gas would have cost for the same distance. (I signed up for Blink Basic now [no annual fee] which will make it $1.50/hr once I get the card). One annoying thing is that you are charged per hour connected, not per hour charging -- so I have to set an alarm to go unplug the car to stop getting billed for it.
No problems with the car, though cabin temperature regulation isn't very stable as others have reported. I don't like the way the defroster works either -- it forces AC on, heat on max, and fan on max when that wasn't necessary to keep it from fogging up. I wound up basically taking everything off auto and setting the temperature and fan where it needed to be to keep the windshield clear while not getting too hot or wasting a lot of energy.