Our stay at the apartment in Edinburgh was dreamy. The location is absolutely perfect for Old Town and New Town. We could walk almost everywhere we wanted to go. And we traveled around a bit by bus too, which was easy from the apartment. Left the City by train, also a short short walk.
The apartment is spacious, plenty of room to stretch out. The amenities worked great. (We used the washer quite a bit and it was simple.) We didn't use the kitchen so can't speak to that, but looked good. Shower/bathroom all good.
The only thing to be aware of is the almost treacherous climb to the upstairs bed. But once you get the hang of it, it's all right. And to be up there with a view of St Giles top at night is pretty magical. The views all around are magic in this flat.
Others have mentioned the 4-flight walk-up which was a drag the first day with luggage but then so worth it (and fine on the way down with luggage).
I would definitely book the flat again. It was special, truly.