The interview process was positive overall, though it is not for the faint of heart — several rounds and it took about 3 months from application to offer. My recruiter (Lukas) did an excellent job facilitating the process and it was a pleasure to work with him.
The first round entailed several sets of self-paced logic questions which took about 2 hours total. Next, two self-paced algorithm questions which took about an hour each. After that, I spoke with my recruiter for an hour long behavioral interviewer which was relaxed and overall enjoyable. Then I had a 1.5 hour behavioral and logic interview with an engineer. Finally, another 1.5 hour interview with some senior engineers that was behavioral and knowledge based with some general questions about Swift and iOS (nothing too tricky).
After that I provided references (which they did check) and received the offer about two weeks after my final offer.
I really appreciated that they weren't just interested in my algo skills like a lot of tech companies these days. It felt like they were evaluating me as a developer and person to see if I fit the position they were looking to fill.
The only negative would be the time commitment, but that's somewhat reassuring because it indicates that they aren't just hiring any random applicant — your team will be filled with qualified, well-rounded individuals.