One of the major selling points of IIIF is interoperability. Besides choice in image viewers there are clever ways in which interoperability can be handy.
Watch this video for an example of how the interoperability of different viewers helped solve a mobile display issue.
Note that Universal Viewer now has an improved responsive mobile interface so this trick is no longer necessary!
We'll see more examples later of of the interoperability enabled by IIIF can benefit publishing institutions and users.