Hamburg is clearly a "must do" if you are in Germany; during winter and end of fall you can have periodes with long grey sky but still overall the city is just AWESOME!
The public transportation system (S-Bahn; U-Bahn & Busses) is just perfect to get around. As well the Airport has a perfect S-Bahn connection and it takes you only 30 minutes to get to the city main train station. (check on HVV.de for detailed timeschedules etc ) Furthermore Hamburg is highly engaged in bringing emission free public transport on the road. MOIA (volkswagen) plans to start a electric " Shuttle-on-Demand-Service" with 200 cars later in 2018.
If you are in Hamburg check out the elbphilharmonie for tickets - try to get the large concert hall - acoustics is just perfect and one of the best in the world!! (The elbphilharmonie has two a large and a small concert hall); If you dont get tickets for a philharmonic orchestra visit the "plaza" and enjoy an amazing view on the Elbe river and habour area.
Elbphilharmonie "Elphi":
www.youtube.com/watch?v=wdq571K1hbg
Additional videos in preparation: Hamburg Airport Lounge / Alster lake timelapes ... subscribe or PM to me if you are interested or have other questions