The process took around 2 weeks. No personality at all during the whole process, putting away all kind of humanity and just calling, doing questions, hanging (no "how are you?" no "well, I am X, I work here at Booking and we do X, bla bla"). The questions were vague, ambiguos ("what happens since you type Booking.com until you see the page?") and without any kind of plan, jumping from one topic to another based on my answer, etc. It looked like a lack of planning. Coding questions are easy but the fact of having people looking at your code in realtime can make you pass through a bad moment.

There was a brief phone screening with an HR when I was asked to explain my motivation, background etc. After that I had a technical screening interview. As a preparation for it I got 4 programming questions (data structures & algorithms) which I needed to submit before the actual interview. The phone technical screening interview itself was held by 2 SW developers who asked 2 technical questions (which I needed to code in their environment real-time) and one business-related question. Last round was basically the whole day in house, 3 interviews. The first interview was a technical one, usual things like coding a solution for a tough problem on paper. The second one was a system design interview (but anyways the guys asked me to code some stuff in the end and I was happy to do so :D). The last one was with a senior manager and was more of a chat, although I have no doubt I was somehow evaluated during this chat. Overall: really nice people and smooth interview process, Booking.com is also quite flexible - they changed the time of the interview when I told that I have another competitive offer. A great overall experience!