I stayed at this hotel for a week long conference and really enjoyed it. It's true that there is not much to do / see in the local vicinity (there didn't seem to be any restaurants or cafes nearby either). A taxi to central Madrid costs around €20. The rooms are really nice and modern with wood floors and comfortable beds, there is a speaker with a usb connection, but it didn't seem to work for me. The bathroom is also lovely and modern, the only slight strange thing being the floor of the shower - it's made of perforated metal, which is not very comfortable for standing on for very long.
I would give it a 5, but knocked one point off as the room service / restaurant menu is very short and not very vegetarian-friendly. Also, there is an iron you can borrow, but the ironing board is a portable, tiny one, which makes ironing adult clothes quite tricky!