Ryanair did it for two summers, so I imagine the first round couldn't have been awful for them. Despite Nordica's brave attempts to market Edinurgh to Estonians it is probably mainly a route for UK->EE holiday traffic though.
Ryanair are probably more likely to be able to attract that type of customer than an Eesto-Slovenian airline called Nordica that nobody has heard of, and that is quickly getting an awful reputation among people that have heard of it.
(I've never actually managed to fly with them yet, so I can't comment. So far I've booked flights via CPH, via AMS in the evening, and to or via EDI. All of them have been cancelled...)