If customers were unhappy with Ryanair the airline would not expand that rapidly. They just ordered 100 brand new Boeing 737-800 aircraft and expect an increase in passengers of 25 percent per year. That is quite a lot. If Ryanair would fool their passengers they would never fly again with Ryanair.
It is not a coincidence that Southwest, Jetblue, Ryanair and Easyjet are doing so well at the moment. People want to travel more and more, and pay a reasonable amount of money for their ticket. It is perfectly acceptable for most of them that you arrive in a regional airport and have to use a bus to get to a railway station. Or hire a car and continue their travel.
One of the advantages of the airports Ryanair is using is that there are no delays. It is amazing how fast a turnaround is done at Charleroi or Brussels South as Ryanair likes to call it
. And arriving is great, leave the plane, go through customs, no long queues, pick up the bags and you are out. All this is 15 minutes or even less. Not to speak about the low costs for parking your car. All this appeals to travellers who are not willing to pay enormous amounts of money for parking (are you reading FRAport?)
People who think Frankfurt Hahn is THE airport close to Frankfurt are also the people who have never heard of Ryanair. It is the kind of traveller who visits a travelagency to book a trip there. Do not think a lot of travelagencies will suggest their customer to use Ryanair, but that has nothing to do with the quality Ryanair.
The more experienced and budgetwise traveller , and there are a lot of them, know Ryanair, know how to use the internet and how to book, and find out how to travel to your final destination from the airport you arrive. There will always be the traveller who books a flight on Ryanair lured by the low fare and finds out after arriving the airport is not the airport he or she expected to be out. As said by another poster, this can hardly be blaimed on the airline.
No, most complains on Ryanair comes from their compatitors.