My third semester of Masters in Mechatronics engineering, I decided to spend Erasmus semester in University of Hamburg.
I am working on my thesis, the research environment is very nice in University of Hamburg and I am in Informatics department working with Knowledge technology Group-WTM (http://www2.informatik.uni-hamburg.de/wtm/)
Hamburg is a city full of culture and international Interactions, One of biggest in Germany to host foreigners after Berlin and Munich. Hamburg port is one of the largest ports in the world. Highly populated city connected with excellent and fast train infrastructure. I heard before coming to Germany that it is very difficult to survive in Germany without German language. I strongly advise that this is a very wrong perception. At every place you can find someone who can communicate well in English.
Things to consider before planning Erasmus in Germany
1) You will have to pay a registration fee of 200-300 Euros; it varies from one province to other. For Hamburg it was 300 Euros. But i believe it is fine because in include the travel ticket for Hamburg also.
2) The official semester time is 6 months in Germany.
Finally, I will conclude that Erasmus in Germany is a lot of fun, including a lot of travel opportunities and high quality education and research.