Probably one of the best, and fastest moving interviews I've done. Everyone I met with was tack sharp, and the question were relevant and fun. These included questions about my research background as well as a few whiteboard coding problems (can't escape those!). They responded about the hiring decision that evening, which I thought was quite incredible.

Lots of questions that looked like they belonged in a lower division class CS final

I re-contacted an Apple recruiter who contacted me in the past because I was looking for new opportunities. After sorting out the location, I got two phone interviews. I got quite basic C++ and algorithm questions. After those two interviews, I was invited for a round of interviews at the Cupertino office. I had 4-5 interviews back to back with no breaks. I really appreciated having to meet 2-3 engineers during each interview. It is actually a good ice breaker. The questions I got were difficult but quite manageable if you came prepared.