The interview process was standard. Two phone screens before they brought me in for an onsite. The phone screens were not particularly difficult, just high level algorithmic questions. At no point in the interview process did they ask any "gotcha" algorithms questions.
For the onsite, they flew me out and put me up in a nice hotel. The location was very close to their headquarters making it convenient for the day of. The onsite was very pleasant and I liked the team. I was pretty excited about the whole thing until the offer stage.
At the beginning of the process, they said they likely could not meet my ask, but that they would be able to meet my current salary. Unfortunately the actual offer was 22k less than I make now, non-negotiable. Of course with all things non-negotiable, when I said no they said they would see what they could do. Two weeks go by and they say they can't improve their offer because I would be making more than their most senior engineers. What this says to me is that they are grossly underpaying their staff so I turned them down.