Ralf Kruse is a guy from Hamburg with his sleeves up that does his job with unmatched energy and focus. You will not hear him bragging about successes, but his customers do this for him. With his energetic and playful attitude and downright honesty, he becomes a valuable companion. Besides his MSc in informatics, he is a Certified Scrum Coach (CSC). You can also hear him lecture about agile at the university. When he works for you, he illuminates the darkest corners of your room and although what comes up is typically not the nicest stuff, he is there for you to help you clean it up.
Some client feedback:
Landau Media http://www.agile42.com/en/references/scrum-implementation-landau-media/
SIX Card Solutions Deutschland GmbH http://www.agile42.de/de/references/six-card-solution/ (in german)