Originally Posted by
mlin32
The German trains aren't very reliable or punctual but I think 2.5h is enough buffer. Don't forget to reserve a seat on the train.
I find the Trams a lot less reliable than the long distance trains, however if you're ever crossing borders (at least from Germany to/from Poland) be aware you may sit for a long time waiting for the respective countries conductors to take over.
Heading from Berlin back to Warsaw last month we waited almost an hour at Frankfurt (Oder) while waiting for the Polish team to arrive coming in from Russia.