Spent holiday there in 2007. Based just outside Ardara. Ditto lack of planning laws make for uncontrolled building of identikit bungalows even to the end of the most remote single track roads ( I live in Scotland where planning is more restricted in scenic areas)
Donegal town lovely and countryside inland very pretty. Liked Letterkenny market town.
Also very tip of Donegal, Portsalon and Buncrana and Moville. They told me many people live in Donegal and educate their kids in Derry can't quite remember but lots of cross border movement on daily basis.