Stayed for one night only and I can only tell this hotel has a really convenient location, near the parliament and the museums quarter, as well as not far from Parque del Retiro or the Atocha station.
The room was quite clean, staff was helpful and breakfast was varied and of good quality. On such a short stay, I'd say this is what you can ask for.

If you want a clean and quiet hotel in a great location then this is your place. The staff is super. The restaurants nearby are also excellent. It is always nice to be near your hotel after thoroughly enjoying sangria.

I had the best EVER 21st Birthday.
AMAZING location, you can walk everywhere! No need for the underground-AT ALL!
Great service.
The price for this hotel is superb! I dare you to try and find better in Madrid.
The only thing I was dissapointed at was the 'Triple' room. 2 single beds and a camp bed for 3 adults is not good enough. My sisters feet dangled off the edge! Will add photo's later! :)

Besides the central location, the thing I likes most about Hotel Catalonia Las Cortes is its ambiance. You feel like you are in a room of a historical palace. Rooms are traditional but new. Staff is friendly. Wi-fi is available and free. Worth staying.