Had two recent stays on points, as the redemption pricing was below the hotels where I normally stay in Madrid (Santo Mauro, Westin, Palacio del Retiro).

Hotel is new and rooms are spotless. SNA for a junior suite did not clear on either of the stays. As a platinum I got an unnoticeable upgrade on one ocasión (exterior room) and an upgrade to a junior suite on the other stay (more spacious, with a bath tube and a small terrace). Some issues with the air conditioning which was loud and impossible to turn off (hotel had to kill it from reception but then I could not turn it on when it got hot again).

Breakfast is excellent, and included for platinum members. I also got 1,000 points (could have chosen a $10 credit instead).

Location is not as nice as the other hotels I mentioned below, but pretty good. More central / noisy if that is the vibe you like.

Service is where the newness of the hotel was obvious. I experienced several issues (breakfast card was not picked up overnight, dry cleaning could not be found, reception not answering the phone when issues came up). Nobody at the hotel seemed particularly concerned about any of these and I assume these are not unusual at this stage.

I would avoid it for business or busy trips (going without breakfast on a busy day because nobody picked up the card is not be nice) but if you plan to stay inside the hotel and have time to deal with service issues / delays it is a good option for redemptions as it is priced cheaper on points than the other 5 * Marriott hotels in Madrid.