I stayed here for three nights in early October. The hotel is an old building at the junction of Goya and Velazquez in the Salamanca part of Madrid. Some find Salamanca a little far away from the main sights but that is precisely why I chose it. It is much less touristy and the main sights are just a very short metro/taxi ride away. You can walk to the Prado etc in about 10/15 mins.
This is a small elegant boutique hotel. The building is quite old, so the rooms have high ceilings, and those overlooking the road have tiny balconies. You can't really stand out on the balcony but can open the french doors and soak up the atmosphere. I had a room with a balcony, and once the windows are closed there was no discernible noise from the street. The decor is traditional, but in a classy sort of way, rather than feeling dated and old fashioned. The bathroom was very spacious, with double sinks, and a full range of toiletries. Some have commented on the showers - they are indeed very powerful and you need to ensure the shower curtain is in place before turning on the water. Rooms were very clean. A generous complimentary fruit basket was provided on arrival. Minibar is expensive as others have noted.
The staff were, without exception, excellent. I arrived at 11am bedraggled from the lashing rain, and there was no problem - the room was ready so I could check in. They even explained that there were two rooms available (with differing bed configurations) and let me choose my preference. They dealt with any queries in a very helpful manner, and all spoke English. We tried a number of their restaurant suggestions and they were all very good.
There are numerous restaurants close by, but they are not as densely located as in the very centre. Calle Jorge Juan is one block away and has a number of very good restaurants. Calle Lagasca, also one block away, also has a number of restaurants and bars. We did not feel the need to go into the city centre any night to eat and had very good food everywhere we tried in Salamanca.
I didn't try breakfast in the hotel, although it looked very good we were always too late - Pan Quotidien on Calle Hermosilla is a very good option close by, albeit not necessarily the cheapest option.
The metro station is literally just across the road, and pretty much everywhere in Madrid is accessible from the metro (the Metro now has a free app which is very useful - if you are lost it will tell you what metro station is nearest to you and will tell you the route to take to whatever metro station you select). You can easily reach the hotel from the airport on the metro in about 30 mins with only one line change.
Retiro Park is just three blocks away and is lovely for a peaceful stroll.
Overall, this is a lovely comfortable hotel, well situated in a posh area of Madrid, with lots of good restaurants and bars very close by. Much calmer at night than the city centre, but close enough to the centre that you can access it very easily. I will definitely stay here again.