I interviewed a few years ago but never got around to posting this until now. When I interviewed, probably around 2019/2020, this place had Glassdoor reviews hovering around 4.8. Now they are around 3.3. I don't know what happened, maybe the HR department stopped doing what they could to curate reviews, but either way, it sounds like the culture at C3 is pretty poor. This was my interview experience.
I first had a 30 minute phone interview with the hiring manager. This part of the interview was pretty straight forward and he invited me to put a presentation together and present it in the C3 offices. The presentation assignment was basically present on an industry use case of my choice. I did the best I could, presented in the C3 offices, and the hiring manager was texting on his phone at the back of the table the entire time. He barely looked up to make eye contact. I'm not going to pretend that I had a groundbreaking presentation, but I thought that this was incredibly rude.
After the presentation, I had a few one-on-one interviews. One of the individuals I interviewed with kept getting distracted and her eyes seemed to follow someone who she saw walking behind me through the window of the conference room that we were in. At the end of our interview, she said "if things move forward, you will get to meet with the CEO who, by the way, walked by a few times while we were chatting." I found this to be a bit odd but also inline with the Glassdoor reviews saying that C3 is toxic, culty, and kiss-up culture.
The reception area of the office almost feels like a shrine to the CEO. Every wall seemed to have a picture of the CEO at some conference or talking on some news show. You can also find a link to buy the CEOs book on the C3 website. All this gave me really weird vibes and to me confirmed the company's toxic culture.
I didn't get an offer, but after the interview, I didn't exactly follow up expressing my continued interest either!