Unlike many others have mentioned, the interviewers were all very pleasant and respectful. The whole process feels like a giant aptitude test, but no crazy brain teasers like many suspect. That means everything listed on your resume is subject to scrutiny. Some questions were not formulated the best way and therefore seemed trickier than they really were. If you don't feel well enough on the day of the interview, I suggest you try to reschedule. You really need to make sure your mind will be at its sharpest on the day of the interview.