We use Booking Manager every day. I like the possibility of having the access to the system from my mobile phone, so even in the evening when I am with my friends I can check the best offers and create direct options or bookings.
We are using Booking Manager now for five years and it has made our work much easier. The program is good in general for running the business and having it all at one place, reachable from wherever you might be at the moment.
Booking Manager is one of our favorite partners, as the API data structure and performance is very good. We especially value the personal contact to the developers and their open-mindedness for constant improvement.