Not so professional HR stuff. They ask you to plan a chat and never follow their schedule. Looks like they think that their company is on top to get back to a person if they decided not to have an interview.

Quick, fast and straight to the point. 3 days at most delay between the interview steps. It was professional, no stupid questions, no time waste. They have a very good interview process, and they tell you at the end of every step if you made it to the other step.