The interview is about an hour and a half.
Interviewer I had was a very nice guy. He first introduced me to the company, and then leaded me into a small meeting room for the interview.
The interviewer first asked me to introduce myself, and then ask me several questions relating to my resume. After that, he went straight into the coding part. No behaviour questions I have been asked, and you have to solve three questions in C++ (mainly C, no OOP needed) in vim. They have test suites for all the questions. The interviewer was seating next to me when I was writing code, and during my coding time, he asked me several basic C++ knowledge questions such as "can you explain what is a pointer to a pointer". I finished three questions early so the interviewer gave me another question, which I only purposed my implementation but did not have to the actually code that.
The interview was not very intense, at least the interviewer tried his best to not let me feel uncomfortable. You might need to think fast during your interview since you have to deal with the coding at the same time answers all the other "easy" questions from the interviewer.