They're pretty common around where I live (as are Teslas, Leafs and other electric cars) and the nicest thing I've ever heard about them is "at least the interior is pretty nice".
1 - http://assets.inhabitat.com/wp-content/blogs.dir/1/files/201...
The interior is indeed nice, and overall, the car is thoughtfully designed. In terms of engineering, I'll argue it's one of the most innovative cars in a decade. That matters to some more than the, shall we say, adventurous styling.
Here's the production model, not too different.
https://upload.wikimedia.org/wikipedia/commons/a/ab/BMW_i3_0...
It's been on the road for a couple years now
I can understand why you feel it is a hideous vehicle, it's certainly not traditionally styled. I think there's a lot more to the design of a car than the curb appeal, for lack of a better term, and with that in mind it is a very interesting car.
I think what seems to be bothering people about the design is how much it deviates from BMW's brand styling. If it came out from Toyota or Nissan or something I don't think people would have really noticed or cared.
I think what's kind of odd is how little media coverage electric cars that aren't Tesla get.