I had interviewed across all of the big consulting firms, including some boutique firms. As a grad student finishing a PhD, I was a bit of a fish out of water, but fared well . . . in other words, I made it to the final round interview at multiple locations and accepted a job offer at one - things have worked out extremely well in the years since. So I'm you're a PhD student reading this, don't be intimidated by the interview process.
This introduction is a bit self-serving, but the purpose is to state the case that I had a very positive interview experience overall, especially for a non-traditional interviewee; I had a very poor experience with Bain. This is the only firm where I did phone interviews. I was scheduled for 2 30-minute cases back to back. As I struggled through the first case - yes, it didn't go very well - the phone interviewer (rudely) interrupted me and told me to stop after ~10 - 15 minutes. He snarkily (is that a word?) recited the 'answer' and proceeded to hang up the phone, leaving me ~15 minutes to sit in silence and wait for the next call, which was the last thing I wanted at that point. If you're wondering, the interviewer hung up the phone without saying goodbye, or giving me a chance to recover my poor start to the case, or ask any questions about Bain. Didn't I still have 15 minutes to turn it around?
You're interviewing me, I'm interviewing you, I get it. If someone presents a poor interview, you don't want to waste your time, I get it. But after a couple of successful years in the industry, I know to conduct myself graciously and professionally, even during interviews, as I and everyone else I work with is an ambassador to my firm. You are Bain, and everyone wants to work for you, I get it. But the level of respect i received at BCG, McKinsey, and all of the other interviews that I gave was not even close to the lack of class and professionalism that were presented from Bain. Blessing in disguise; no job offer from Bain.