They have 10-staff top management, incl CEO and vice-presidents. Sounds alarming for 1 aircraft operation.
The "normal" fare is not much cheaper than BA, then you have no connections, no network, no FFP.
The fare is more expensive than LH DUS-EWR all-J service, but ok, the cabin comfort is really different.
There is a certain risk of delays/cancellations, much higher than on BA/AA/CO/whoelse.
However they could have a business on selling a "serial" tickets to the companies who have a need in the instant senior staff commuting between LON and NYC.
Amount of funds they have raised for this operation (at least what their website says) sounds quite solid. Unless they spent all of it already on a top-management salaries they should be able to fly an empty airplane for a few month easily.