Whats it like to work at McKinsey (looking for answers from ex/employees)

Looking to learn things I might not know before... company culture, how possible travelling a lot is, any cool trips/ experiences you get as part of the job (often perks which are not specifically stated), the best things and opportunities which aren't commonly talked about (there are lots of generic answers about working with the best people, fast learning curves etc but I want to build a more in depth understanding of what working there is like). Thanks in advance for any replies- I'm starting in September and my sister is recruiting for a few firms and industries inc McKinsey atm so she would also like to know more!