Very standard process: some recruiter reached me out on LinkedIn, then I solved some online programming challenges, then some phone screening, then a more in depth interview with other developers, then the company flew me to Amsterdam where I had four round of interviews: one with the recruiter, then two developers, then other two developers and finally a manager who I wouldn't like be managed by.
The interview is very business focused, but I was able to feel what employees describe about the company during the interview: it doesn't seem to be a challenging environment. The recruiter advertises that the interview is business focused because this is the main challenge for developers. Seems like the developers don't agree, as none of the 8-9 developers I spoke with (some during the interview, and others while walking around with a friend of mine) mentioned that impacting the business is one of the nice things of working at Booking.com. Also, being interviewed by people on the company for at most 2 years doesn't give a good impression on how the company is good at keeping people.
The management structure seems to be very messy, and I was able to feel some stress in the air when I asked about other developers working at Booking.com for more than 5, or maybe 8 years, as I haven't _seen_ any developer working there for more than 2 years.