Terminal 4 is a design treat
The wavy bamboo ceiling and warm colors make T4 one of the prettier terminals in Europe.
T4 is set apart from the older terminals, so a transfer there means extra travel time.
Madrid's Terminal 4 genuinely lifted my mood with its flowing roof and use of natural light. It's spacious, easy to get around, and the tapas on offer beat typical airport fare. Just be aware it sits away from the other terminals, so factor that in if you're connecting.