It's less functional, spacious and performant than a much safer all-electric car you can buy today for less money. It has neither DC fast charging capability nor enough electric range to go anywhere reliably (22 EPA miles in ideal conditions). It has all the maintenance hassles and costs of a traditional ICE plus whatever they are for BMW's electric technology.
The i8 is an old-school gas guzzling supercar that happens to have a battery inside it.