There was an Interview with Tow Ubukata on ANN a while back where he talked about the limitations he had when working on Psycho-Pass 2 given that it was squeezed in front of the movie... as it turns out that isn't a good excuse as to why it was so lackluster then the movie works really well as a standalone entry. The existing characters besides Akane and Kougami get very little screentime so they had plenty of freedom.
Anyways, the plot isn't all that movie worthy but the export of Sibyl-"Lite" adds some needed world building as to there the system stands in the world. Since this all plays out abroad in a tropical setting it feels different from the show and the action focus is a lot bigger. It is sort-off filler (depending on Kougami's future role) given that there isn't much lasting impact to the general "universe" from these events.
The animation and action is done well and an upgrade compared to the show plus the dominators wreck a lot more havoc with extra focus on the guts.
All-in-all it's a solid action flick for me but not much more.

(If you haven't seen the show you could watch the movie anyways as the gist of it gets explained in the OP but I can see some head-scratching without any previous knowledge of the show).