Terrible working hours (I was a consultant there for over 4 years and averaged 85 hours per week with many, many memorable 100+ weeks)
Over the course of my tenure, I saw how the grueling hours and stress led to physical and psychological degradation of great people. One of my colleagues would suffer seizures because the medication he normally took for a chronic condition made him drowsy, and he couldn't afford that additional drowsiness when already sleep-deprived on our projects.
Another colleague developed a stress-related condition so severe it was mis-diagnosed as breast cancer during the few medical visits she was able to make without repercussions from management.
When a manager of mine who was pregnant in her first trimester would leave the boardroom due to morning sickness, (ie. go throw up) our higher-up manager claimed it was "unacceptable for her to just leave the room": he also claimed she should be grateful BCG made arrangements for her to work there while pregnant, since "women getting pregnant was their own choice" (and not, say, a fairly important biological imperative of your species).
That BCG institutes a metric system to track work/life balance is indicative of how much of your life will be under its control when you work there: all of it!
These are insane costs to pay for prestige and learning.
