I'm just amazed at how many flights Wizz run to eastern European destinations. Yes, there are certainly many immigrants from those areas, and I expect most flight passengers are returning VFR, rather than new immigrants. I'm just surprised that Ryanair and Easyjet haven't tried to get these markets by expanding to such destinations (perhaps they have?) from Leeds or East Midlands, as many passengers I've spoken to are from a much wider catchment than South Yorkshire.
I do remember when the route from DSA to Vilnius was introduced a few years back, to much incredulity. Now it's commonplace. I had to look up Lublin as I'd never heard of it.
Obviously, I hope Flybe do well, and I hope to be going to Berlin soon, but as a cautionary note - and this is purely anecdotal - when Ryanair and Thomson, later Easyjet, introduced routes, a lot of people I knew used them as a one-off novelty chance for a holiday or long weekend, and didn't repeat this. Flybe's medium-sized craft are perhaps more suited than 737s or A319s.
Finally, it would help if clear directions were given at the bus stop how to get to Sheffield, in many languages. You could get a bus to Doncaster then get a train, but if not in a rush could get a day bus ticket on First for £5 and take the X78 from Doncaster to Sheffield.