The process was ok, overall. Unfortunately, it can be hard to get on their radar without knowing someone to refer you.
After two rather "fit-based" phone screens, you will progress to the onsite.
Having answered a lot of fit questions over the phone, I expected that the 4 onsite interviews would be technically oriented, especially for an engineering role. The first interview was a somewhat technical system design + testing question, with two QA engineers; this was the most pleasant part of the experience. I felt like they cared about my thought process, my communication skills, and technical aptitude.
The following three interviews were all fit-based, and had very similar questions from one interviewer to the next. Responding to the same culture-based questions three interviews in a row was a little dull and gave the impression that the interviewers were not coordinating their questions. It also gave the impression that their hiring process is not data-driven, but rather fit-driven. If you learn a small amount about QA you could definitely fake your way through their process, which is not true of most tech companies.
Overall, a good experience, nonetheless. I wish I had time for a bathroom break.