Right after my first trip through Tegel, a few observations :
The taxi rank is bigger than the airport.
As Mark aka Jim eluded to its just a corridor, its like they built the airport and then remembered they have to put the people somewhere, the check in queues intermingle and block the said corridor.
They then wouldn't open the gate to let people through to security for an hour, when they did, three flights and one passport control bloke, who to give him credit over his English counterparts was at least cheery.
Then you end up in the departure lounge which is worse equipped than Stafford railway station, I was so glad to get on a flight regardless of it being an hour late !
I never thought I'd pine for Frankfurt airport, the half marathon cross airport dashes, the car hire that is situated in another time zone it's that far away, the multiple security checks if you fly with BA, the autobahn 5 that there is always a problem on which makes you later than you'd like, but at least at Frankfurt people smile, they actually want to be there, Tegel was the airport of the damned and I should imagine is exactly what purgatory is like.