I sent my CV for them after I saw the job offer on Stackoverflow. I think it took 2 weeks till they mailed me and arranged an interview.
The interview was in Skype, Interview panel were their HR manager and one of their software team leads. They were vary friendly and nice (They even noticed my birthday is near which is kinda cool :D). The interview was more focused on getting to know me and I getting to know their company. There were some small technical questions but not hard ones.
From their explanation I know there is three stage of interview:
1- Skype introduction
2- Technical interview (probably in Skype again cause I don't live in Germany)
3- On-site interview (Getting familiar with office and collages)
I had really good feelings about the first interview but after almost 10 days I got an email that the position has been canceled (unlucky me).
Overall I had a good experience talking to them and IMO this is a very nice place to work.