I did like the breakfast: there was a lot of choice, I liked the seasonal fresh fruit counter. I would agree that the hot dishes were the weak links of it though. Agreed also about the blinds and curtains which were weird. Basically there are no way to open them, not that you would want that in Summer, but in November I wanted some natural light inside.
MAD is a huge airport and distance have to be taken into account. For T4 the subway would be much more convenient. Note that there are lifts from the street to the platform at Feria de Madrid station.