Pros
You want to learn? Yes, you'll learn. Booking.com was (and still is) at the peak of innovation when it comes to UX writing. When I left I realised just how many lightyears ahead of most other companies we were. In the early years it was the people who made the place truly magical, but I am unsure if the same spirit has survived the growth. During my time there I met some of the most inspiring and competent professionals I know.
Cons
I was there during the most intense growth period the company ever had. Our team expanded at high speed, our roles were not clearly defined, our responsibilities were increasing with no clear adjustment or compensation. Management was well-intentioned at best, unsupported, and severely disempowered through a combination of experimental structures and a total lack of understanding and follow-through from leadership. This resulted in frequent and severe burnouts and contributed to the development of a toxic environment. During a short time, the faces of Booking's leadership had finally started to look more diverse, but sadly this did not last. For a company flouting diversity and care for their employees I'd say: you can do better.