Excruciating. It was 4 or 5 stages, and took place over the course of 2 or more months. They flew me down to California for the final round to interview with some sales directors, and I felt like it went pretty well.
I had only been out of work for a short period at the time, but they were a little pushy about the current gap in my resume. I let them know I had been actively applying (and interviewing) across the industry, but it was Mid-2020 and the world was still in upheaval. I let them know I'd been focused on some hobbies as well, which lead to a nice conversation about Donkey Kong Country, and the neck tie I had sewn for myself specifically for the interview.
After hobby talk, they still insisted on knowing where else I was interviewing, but they became a bit adversarial when I let them know that I was also in the process of interviewing with one of their biggest competitors. We talked through it, and I explained why they were absolutely my first choice, but that in my current situation I couldn't afford to put all of my eggs in one basket.
Overall the final interview went very well, my skills were a great match for their needs at the time, and we had a lot of great conversation. I walked out feeling good about the interaction despite their reaction to who all I had been interviewing with.
When they called to let me know I didn't get the offer, I couldn't get an explanation from anyone as to why, and they completely ghosted me after my follow ups.