The inteview process is intense at Appirio. Largely, this is in an attempt to gain a better understanding of the candidate's skills as well as they're cultural fit. Culture is everything and even one of the CEO's top priorities with the company.
I, myself, went through 11 interviews, before getting an offer to join Appirio. While this is a lot, the process was smooth, and the recruiters and coordinators did a fantastic job of keeping me in the loop.
The general process is: Recruiter phone screen, possibly several other phone screens (more recruiting, but usually with the functional team you'd be working with, and then past that it's inperson where you might meet with 6-8 people from the company which can include anyone from associate level to the most senior level.
The in person interview stage can be a slog to get through, but meeting and speaking with that many different people was able to give me a great insight to the company. Just be prepared to take that day off, as for me at least, it was a little draining.