More broadly, physically being at ESO provided a number of additional benefits. In general the research environment there is conducive to collaboration outside of my planned project, simply due to the interactive nature of the campus. This is especially true within ESO, but extends to the neighbouring facilities such as the Max Planck institutes. During my time there, I was able to participate in a wide range of activities that I believe have improved both my specific research and broader academic skills. I was able to present my research in a number of situations, undertake various workshops on professional/academic skills (including ERC grants), and discuss with instrument scientists and User Support Department staff about any detail of the ESO facilities I am using. I participated in the OPC as an assistant and learned a great deal about the telescope proposal process. I developed further collaborative links to staff and students around the campus that will persist beyond the studentship. There is a great deal of discussion that occurs throughout a given week on campus, including seminars, Journal Clubs, and others, and this helps to broaden the exposure to whatever is state-of-the-art in a given field (outside your own) which helps get you out of your niche research rabbit-hole.
I would recommend the studentships to all PhD students. It is important to establish a clear project in which you will benefit by being at ESO, but for anyone with collaborators at ESO or working in a field with a strong presence there should not find this difficult.