The whole interview procedure took 1 day. I had 1-to-1 interview with two professors, about 20-30min each. Gave ~30min presentation about my Msc. thesis. Afterwards lunch with the research groups I would work in and extensive lab tours and time for discussions with other PhD-students/postdocs from the group. Overall very friendly atmosphere. Received an offer right away and was able to choose between two different research projects.