Each interviewer, including the CEO, acted as if they did not want to be interviewing me, even though they kept moving me along in the process. The interviewers did not initiate any pleasantries or conversation, and each interview was approximately 40 minutes of an interrogation-like Q&A. When they did comment on my answers, it was sometimes to respond condescendingly. When I asked the CEO questions about the company, he would respond in question form and avoided answering definitively.
Each interviewer also asked a brain teaser. These sometimes took up to 15 minutes and in my opinion, did not help them understand me as a candidate beyond perhaps testing my patience. The entire interview process seemed to serve as a long arbitrary exam instead of an opportunity to learn about a candidate's professional qualifications.
The company seems to also view their candidates through the lens of their former high school and college selves. I was asked for my SAT scores during the preliminary application process (the real test was being able to find them!), and most interviewers told me this was their first job out of college.
Some of this pain was self-inflicted; I continued to move through the process in hopes that the first interviewers were not representative of the culture at large, but out of several interviewers, I only had a pleasant experience with one.