Frank's house is lovely. It is very clean & well-appointed. There are extra linens and the kitchen has enough pots, pans, & utensils that you should be able to cook meals with no trouble. We cooked almost all our breakfasts & dinners at home for the week we stayed.
The views are incredible & the apartment is really beautiful, as well.
One of our party slept on the couch & it was perfectly suitable. The couch-bed is not as comfortable as the bed, but it works just fine for one person.
The location was perfect for us. We were able to walk almost everywhere we wanted to go, and we took public transport from the airport to the house--the metro stop is just around the corner from the house. We went an entire week without being in a car at all.
The apartment feels very private and safe. The stairs are very steep, but we adapted pretty quickly & it wasn't an issue for us--though I would worry about older or less able people climbing & descending stairs so steep & narrow.
Frank is very responsive & helpful. We had a great stay at his house!