Psycho-Pass: Sinners of the System is a trilogy of films set in the Psycho-Pass universe (and as a direct sequel to the two anime seasons). Each film is an hour long and focuses on a particular "case" and a particular set of characters.
The first case, titled Crime and Punishment, follows inspector Mika Shimotsuki and Enforcer Nobuchika Ginoza. After witnessing a car crash, the pair eventually track down the woman's history. She works at an experimental prison where criminals with a high crime co-efficient are sent off to live. However, through a combination of drugs and therapy, this has a surprising result. The latent criminals are able to function as a peaceful society. Naturally, Mika is suspicious of the warden. Once the characters step foot into the prison, the story moves forward at a steady pace. You can get a feel for what this trilogy of films is going to be about, being how even with the "perfect" Sybil System identify criminals before they commit their crimes, that there are still people able to exploit that system. It doesn't have enough time to go in-depth with its themes, but it covers enough to remain interesting and satisfying.
The second part of Psycho-Pass: Sinners of the System, First Guardian focuses on the enforcer Teppei Sugo. The story dives into his background as a well regarded soldier and how he ended up becoming an enforcer. Therefore, the first part of the movie does not feel like Psycho-Pass at all, as it shows off Sugo's time in the military and the tight knit group that he was a part of. However, pretty much his whole squadron is killed during a mission and he is the sole survivor, and this gets wrapped around a terrorist attack. Assigned to investigate this scenario are the enforcers Aoyanagi and Masaoka. The film is a tad bit less interesting than the first, despite a higher frequency of action sequences. It's probably because it was so focused on past events that it doesn't deal with the themes of Psycho-Pass until near the end. Having the Sybil System touted as so perfect and absolute, yet there are still so many people with high crime coefficients that have slipped through the cracks until now. It does highlight what a stressful society it has become, since you would always be worrying about your own mental health. It's not amazing or terrible, but First Guardian sits right in the middle.
The third and last part of Psycho-Pass: Sinners of the System follows Shinya Kogami. Kogami is working as a mercenary in Tibet and since the whole film is set outside of Japan, the Sybil System doesn't really make much of an appearance. Sure, it is mentioned once or twice, but on the whole, the link with the anime is a tad bit weaker. On the other hand, it shows what Kogami's life is right now and despite being a wanted criminal in Japan, his sense of righteousness has not diminished. Sure, he can be too idealistic and cold at the same time. The plot has him encounter a young teenager who is bent on revenge for the mercenaries that had killed her family. As Kogami has experience in revenge, and actually succeeded in it, he reflects that it is not the best path to go and expresses his remorse. This takes up most of the time and the film's pacing can be on the slower side, but thankfully never gets too bogged down. Overall, just like the other two parts, it is average, not boring but not amazing either.