We absolutely loved our stay at John's cottage. It's a 150 year old listed building so don't go expecting a 5 star hotel and you'll be grand. We didn't use the cooker or washing machine so can't comment on those but we did use the microwave and fridge/freezer and tbh they were cleaner than ours at home! The water is coloured because of the area, copper etc, it is safe to drink but we bought bottles of water for making tea.
The beds aren't hugely comfortable but we didn't mind that much as the cottage itself has a certain old world charm and the location is spectacular. It's an ideal spot to base yourself for a trip around Inishowen.
Our kids loved going out to see John tending to his sheep, horses and cows every morning and evening if we were back in time. We loved it that much we booked for a return trip before we left.