This being me, I'll get my gripes out of the way first - the trains, drains and smokers. The S-Bahn trains are disturbingly British in their tardiness and overcrowding but very un-British in their lack of decent ticket machines - even Germans (assumedly not of Berlin) were struggling and the Messe station had only four machines to deal with hundreds of travelers at peak times. At least it was also un-Britishly cheap. As for the drains and smokers, both stink at all hours of the day. Staring at the awe-inspiring architecture is somewhat dampened by regular gusts of eau de turd and you can't get a drink or a meal out without getting caked in tobacco smoke.
That said, the whole place is an architectural marvel. It is massive in scale and they aren't shy about mixing large open spaces, parks and huge (huge) buildings. Everything (other than the smell) is clean and there seems to be a huge amount of construction/repair work going on, giving it a feel of an industrious but culturally packed place. For a major European city, it is relatively quiet, helped by how spaced out everything is. The only real visits I managed were to the eerie Berlin Memorial wall and the Bauhaus Archiv, but passing the Brandenburg Gate, Reichstag and various memorials, museums and mix of architectures left me wanting to come back and explore some more.
That and the rather excellent culinary scene...
