One word - Horrible! Just turn away and apply somewhere else. Where do I start?
The process took more than two and a half months. I was unpleasantly surprised by this and added to the fact that the recruiter ghosted me 3 times during the process. At one stage, my primary recruiter left the company and no one bothered to get back to me with the next steps.
After the entire process, I was not provided constructive and descriptive feedback. One of the interviewers had no idea about how A/B tests work and challenged me on the methodology. When I provided her the explanation, which was backed by her own colleague, she held it against me.
They expect you to provide the answers based on real data, which they never actually share, and when you don't they call your answers 'hypothetical'.
I found the entire recruitment process at Booking.com to be shabby and unsynced with recruiters ghosting, long time frames without updates on the next steps, and finally providing vague feedback like the aforementioned.
Avoid this company for your peace of mind, there are better employers in the market.