One of their key design features was to keep it "fun to drive". On the i3, the curb weight is 2700 pounds with 168 horsepower. I've taken my buddy's Honda Fit EV out several times now, which is 3252 pounds and has a 123-horsepower electric motor and it is SUPER zippy in Sports mode (Sports mode is the max 123 HP). So shaving off 550 pounds and adding 45 horsepower is going to make the BMW EV a beast to drive!
I've been mulling over their design decisions. I think they went with the extra performance (weight to HP ratio) to make sure that all of the reviews of their first EV product were stellar as far as driving it goes, which will give them a great initial foot in the door for a future electric market, because word will spread that driving an electric BMW is awesome. And I should note that the Fit EV even had plenty of pickup with 4 adults in the car - my last 117-horsepower ICE Fit would get pretty dang sluggish with that many fully-grown bodies inside...
As far as the aesthetic design goes, I suspect that they made it quirky to cover up for the low range. You can only drive about an hour or so with an 80-mile battery (or double that with the gas range extender), which is pretty low for a high-end car like a BMW, especially when Tesla comes with an optional 200 or 265-mile battery pack. So I think they made the car look funky so that people would look at it and say, hey, it's the new electric BMW car! It only gets 80 miles of range, but it's fun to drive and you don't have to buy gas! I think if they had stuck with a traditional body design with only 80 miles of range, that would have (eventually) put off EV buyers who want a $45k electric BMW, only to find out that it hardly goes anywhere. So I'm guessing that when the battery technology improves, we'll start seeing them in more traditional designs. So like a 4-series with a 300-mile range or a 5-series with an upgrade 500-mile range. So by then, they're treading on practical-range territory, without the risk of tarnishing their existing brand by having a car that looks like their other cars without having all of the features (i.e. range) that the gas models do.
So that's my take. It will probably be awesome to drive, but the design looks weird (and didn't have to), but that way people will forgive the low range because they will instantly recognize it was an electric car, not a "traditional" car that should have traditional range.