The only things that were somewhat difficult is when I was asked detailed questions about computer architecture concepts I had little experience with. For example, I was asked to explain out-of-order instruction execution. This is something I am familiar with at a high level, but have never had direct experience with, and in fact, it wasn't a direct requirement for the job. Overall, the interviewers were just asking me questions about their area of expertise even though expertise in that area wasn't required for the job I interviewed for. I found this a bit strange.
