You stay outside the locked business - there is a lobby and 2 meeting rooms. My first interview was pretty swift and easy going. A friendly but busy engineer. I came back for a second round with a person pretty high up. He was intelligent, a good read of people and really listened. No standard large company questions. Walk me through your resume, asked about experience, provide 1 strength and weakness. The money isn't like Johnson Controls or GE but then neither are the politics. People seemed genuinly friendly and were less guarded. Both interviews took about 90 minutes.