This Hotel is centrally located and is good for most amenities however, it is in the scruffier part of Madrid and you need to be aware that homeless/beggers in the small square outside and the area generally. ( Also pick pockets 'track' you in Gran Via)

Avoid being allocated a ground floor room at this Hotel as they are actually below ground level and have 'false' windows.
I also would not rate it as a 4 star Hotel, although its not bad for a 2+.

This is a very nice hotel in a convenient lcoation between the Sol and Callao metro stations. We encountered some problems upon arrival -- rooms were not ready when we showed up, and the first two offerings were unacceptable -- but the hotel manager and staff were extremely responsive and made everything right with minimal hassle. Beds were very comfortable, rooms and linens very nice, and the temperature well-regulated. Our bathroom sported an enclosed shower with multiple heads and sauna-type sprays (the city of Madrid actively discourages baths because of water shortages).
There are some seedy characters hanging out around the hotel, making noise and looking a bit intimidating. But they really never bothered us and the rooms are very well soundproofed.

Why not 5 stars? There were just enough things that were not right upon arrival to keep this just below 5. But we would definitely return and highly recommend the Palacio San Martin.

This is a very good choice in Madrid: clean, centric location in a quiet area. Make sure you ask for a room with a view!

The location of this hotel -- just a few blocks to the Palace, to Sol, or to Gran Via -- could not be better for walking around the heart of Madrid. And yet despite being in the center of this late-night city, this hotel is on a quiet square next to a convent. (My husband can't sleep if it's not quiet, and he slept well here.) The room was modern, and had all the quality you'd expect at something like a Marriott. Reasonable size room, and bathroom to American standards. Breakfast was a very nice full-featured hot and cold buffet, served on the 7th floor with a nice view over the city.