I flew there (from Newtownards) in April, my first foreign destination. Marvellous location, parallel to the beach in a beautiful corner of north west Ireland, it's worth going just for the views in and out. NDB and TDME to help you find it. 1300 metres of tarmac. It's in a class C zone with just one controlling frequency. There is commercial traffic (an Eastern Jetstream departed and an Aer Arran ATR arrived and departed in the half hour we were there) but no trouble going in or out, just a normal downwind join and a no delay departure. GA parking next to the terminal, no formalities other than a customs form which was pretty much the same as a UK GAR. Small cafe on site. Sadly, we were delayed arriving by a weather divert (to a very helpful Londonderry / Derry / Eglinton) so didn't have time to leave the airfield, we had fancied a taxi to the beach which looked glorious. I have been told since that there is no need for a taxi because the beach is less than a 1 minute walk from the front gate of the airport
Avgas available, 12 Euro to cover landing and two hours parking. No handling charge for non-commercial movements even though someone was on hand to lead us out and help my less than mobile Dad into the aircraft.
Another airfield rated "highly recommended" by me!
Full details here:
Donegal Airport Technical Information, Carrickfinn, County Donegal, Ireland