The German blog drohnen.de has a good overview on German drone regulations.
The basic outlines are
- You need to have a liability insurance covering drone flight.
- You need to make sure you are flying in an unregulated zone – this is responsibilty of the pilot.
- Up to 5kg, no license is needed, if there is no commerical intent.
- As a hobbyist, your drone has to be in a radius of 200-300 meters and a maximal height of 30 to 100meters.
- The drone has to be visible in the pilot’s line of sight at all times.
- Any commercial flight need a license and official permission, even under 5kg.
The official law texts can be found at luftrecht-online.de