After a brief phone screening, there was a single interview with both the technical people and with HR.
The HR part was very much like like any other: brief introduction of the company, questions about motivations, etc.
The technical part was more interesting. At the beginning there were some basic C++ questions, then I had to review a short C++ code, which was written with no structure. It looked like some C style legacy code. I think the goal was to explain why this coding style is not maintainable, which was not particularly hard. There were some algorithmic questions (solve this problem, how would you solve it for N?), which I unfortunately do not recall in detail.
Everyone was eager to answer my questions about tools, working methods, and the job itself.
A word of advice: try to arrive exactly at the given time, and not much earlier, since the building doesn't have a proper reception area, just two very small and uncomfortable chair next to the entrance.