Well prepared panel with questions that aimed at testing ability to resolve technical problems in real time with a small amount of information available and with the pressure of time to deliver on a range of potential solutions

Pretty standard phone screen: shared my personal background, professional aspirations and then they shared background on company, the position and answered any questions. Standard tech screen followed-- average difficulty. Anagrams. No curveballs. Friendly interviewer. Final interview was "virtual on-site". About 5 hours total split across 5 sessions. First was another pairing challenge that involved trees and file paths. Then there was a standard behavioral interview. Following that was an OOP interview-- but it was more of a conversation. The challenge was a standard OOP interview topic, so nothing crazy. Talking about design decisions and SOLID principles, etc will get you points, of course. Then there was a systems design interview in which I had to design a popular social media site. Last was a conversation with an engineering manager, which was a conversation about my background and experience. I also got to ask a lot of questions of my interviewer, which was nice. Overall, I had a positive experience in the interview process. It was a simple straightforward three step process. Didn't waste my time or theirs. The folks at every stage were cool. Unfortunately I did not prepare enough for the systems design interview and fell flat on my face which, according to the recruiter, was the only reason in the "No Offer". Overall, still a good experience. The recruiter gave me a lot of feedback afterwards, unprompted. Always reflects well on the company/recruiting process when that happens. Much better than a generic templated rejection email.