Sorry to drag up an old thread here but thought it would be worth mentioning too
I visited while on holiday in Hamburg a couple of weeks ago - pictures and videos seriously cannot show or describe the vastness of this place - it really has to be seen to be believed!!
Not only is the place huge but the detail is ridiculous...even down to as it gets dark (which happens every 15 minutes, courtesey of a clever white, red and blue lighting system), the railway station lights flicker on as if they are fluorescent tubes and lights in the rooms of buildings also go on and off as if to replicate people actually living there and moving from room to room!
Within the Hamburg area, there is even a mini Miniatur Wunderland, complete with mini model train! No detail has gone unnoticed!
The control centre would probably rival quite a few control centres on real railways for size and complexity - there were some 4 or 5 people milling around settings routes and such and I lost count how many screens.
Something I didn't get to is the backstage tour, done in both German and English but would love to do it again if I went.
Currently they are completing a model of Hamburg Airport - I think it supposed to be completed within this year, with further locations due to be constructed between now and 2014.
One final thing if you do visit is I would strongly recommend reserving tickets online prior to your visit - currently this requires no advance payment and means you will get into the attraction within 10 mins or so - allegedly at the time we went, queuing time was up to 2 hours for those who hadn't!
If anyone wants to see any other pictures, I am happy to post some of the ones I took - in some cases you can't actually tell it is model due to not getting anything outside of the model world in the image!