You might be confused by the mix of good and bad reviews for this apartment and I believe the reason for this is clear. The host, Maria, has chosen to keep the cost low so amenities like WiFi are not there and people expecting everything at a price below half of what you would pay for a typical hotel are complaining.
We loved:
The location. It is on one of, if not the, oldest streets in the city and steps away from the Opera, metro, Royal Palace, Calle de Mayor and much more.
The host. Maria, and her co host Gustavo who checked us in plus delivered new pillows, could not have been nicer. Maria had suggestions for things to do/see, places to eat and drink, where to find a doctor when I was unwell, where to park (this one suggestion saved us 250 Euro’s during the week we were there.)
The apartment. No question it was simple but had a large enough bedroom, bathroom, kitchen and the lounge had a futon and large dining table and chairs.
There are a couple of things that were not problems for us but you might not like:
No WiFi (we went to either Starbucks or a local coffee shop)
The shower has no shower curtain (because Maria finds they are hard to clean) Perhaps a shower door would help avoid getting water on the floor.
There are bars and restaurants on the street so later in the evening there can be some noise but nothing that kept us awake.
It is on the 1st (i.e. American 2nd) floor so there are a few steps.
Bottom line. We were very happy we chose this apartment for our stay, the location is unbeatable and value for money is excellent. If you go with realistic expectations you will be pleased.