One thing that stands out to me about the process is that everyone gets the same interview, doesn't matter if you are fresh out of school or have a lifetime of experience. Experience counts for nothing in these interviews. Can you design twitter in 40 minutes, thinking through every possible failure mode and issue along the way, or not? Apparently, I can't or not well enough. I think these companies really want folks with great public speaking and whiteboard skills - I'm kind of an introvert and that is a challenge for me where the day-to-day work is not.