Energy density is "good enough". Cities like New York banned helipads on the top of high-rises after the Panam crash in the 70's because of the risk of jet fuel flowing down a high-rise and igniting.

Electric powered vehicles like this would solve that issue and allow quick travel around high density cities, they could land on top of buildings to pick up passengers. Current battery technology should be enough to support these short range trips around a city.

A good example would be a corporate executive traveling from their NYC headquarters to the local airport to board their business jet. It's not a long distance trip but helicopters are not suitable.