Sweet little flat, perfect location in the historic centre, the Metro (Museo) and supermarket (Carrefours) 5 mins walk away, we were also 5 mins from the museums we really wanted to go to. We even ended up coming back for lunch one day. Everything clean and welcoming, bathroom airy and spacious and kitchen very well-equipped - we liked making coffee each morning. The little outside courtyard (which I expected to be like a semi-public entrance on the way in to the flat) was better than expected, completely private to the flat and not overlooked.
One thing to note, I think if you have any mobility issues, you might find certain things tricky - quite a lot of stairs up to the flat, the shower was I think slightly smaller than the UK standard size, and the wooden steps up to the bed mezzanine also have a bit of a knack to them. None of it was a problem for us but other guests may like to know.