Did a quick trip to Madrid last Wednesday night, coming back Thursday lunchtime.
First impression of the new terminal - it is enormous, our Gatwick flight came into a gate at one end of it and as you got onto the main central walkway the terminal just stretches away for literally over a mile into the distance! Just like a scene out of a science fiction flic. Quite beautifully designed as well - Richard Rogers gets points for aesthetic beauty.
However, and this is a big however, the distance to travel to get to the taxi rank is just ridiculous! As hfly notes, it is over 30 minutes to get out (and this being first off the plane late at night so no queues anywhere). Also as noted, don't take the escalators down to the shuttle train, the lift is much quicker.
Coming back, the Iberia lounge is a pig to find, signposting is pretty poor, Starbucks is the thing to aim for then hopefully you can see the entrance from there. Was disappointed that they haven't improved the lounge over what they used to offer in the old terminal - it is long and thin as others have pointed out and the food selection is as miserable as ever. Also couldn't get wifi to work in the lounge but they do have a few desks just past the food counter with free internet connections for you to plug your laptop in using a standard network connection (if you don't have your own LAN lead, you can borrow one from the front desk).
Also noticed they had a dining room at the end of the lounge that was shut when I was there early afternoon - presume this is for some sort of pre-flight dining for evening long haul flights.
Spent far too long in there as all flights back to the UK on Thursday were delayed > 3 hrs due to the French revolting again.
My experience of the Madrid terminal has moved me to write a letter to Mr Rogers to congratulate him on his beautiful design and to implore him to never build one like it again! Please don't let this longitudinal design be the future of airport terminals! Surely there must be a way to design a terminal that can cope with the required capacity that is more evenly distributed (ie so if you looked at the distribution of walking times to each of the gates they were broadly similar) - strikes me you could do something round a hub and spoke type of system with mini-hubs radiating from the spokes. This would be a development of the design of somewhere like AMS where they have an arc with spokes radiating off and hubs on the spokes. I fear that it may be too late to stop this trend though - from memory some of the newer sections of FRA are like this and T5 is off this longitudinal ilk (though of a smaller scale and with the satellites being closer).