Having been to a number of railway museums in Northern Europe I have to be honest and say that this is not the best for looking at actual trains. There is only a few (well maintained) trains on the ground floor (for obvious reasons). The other floors focus on the history of DB and the DDR equivalent. Hats off to the museum for including the DDR aspect. On the top floor you will find the children's play area and this place is great. There is a small train you can sit astride and lots of other great activities. The model railway is certainly also worth a look - very impressive in a German sort of way. The restaurant is also good. So, the museum is definitely worth a look, but you will not be able to spend a whole day there.
If you own or manage DB Museum (German Railway Museum), register now for free tools to enhance your listing, attract new reviews, and respond to reviewers.