My interview started with a telephonic interview from HR. It was a basic, introductory interview with basic interview-like questions. After passing this interview, I gained a telephonic interview with the hiring manager. It was still introductory, high-level questions. But this time more specific to the position at hand. The hiring manager was nice, polite, and kept to the script. Then came the all-day face to face interview with 6 to 7 senior ranking department heads. This was a much more informative interview where I found out more about the position from A to Z, and what/who they are looking for. All interviewers were top-notch. I felt very comfortable all day. In fact, I began to think I "had this in the bag." As I found out more, I realized this job had my name and capabilities written all over it. I could do this job well. And tried to convey so, as effectively as I could.
The next day, I sent personalized "thank you" emails to every interview team member. Did not hear a response--which is okay, I didn't expect any. One week goes by. Two weeks go by. And I finally send an inquiry email to one of my contacts. The next day, I received a form rejection email from a "do not reply" email address. "Thanks, but no thanks." No explanation as to why.
I've ranked the interview as difficult because of the time involved--not because the questions were grueling. Overall, the interview process was positive even though I was surprised with the outcome.