One of the most well thought out shows that I have ever seen. Characters are introduced several episodes if not seasons before they become actually "relevant", and yes that is a ay with words if you've seen the show.
My favorite part about the show is it's concept of human/ASI infallibility. The show revolves around the main character, Mr. Finch, who after designs an omniscient "machine," grows disallussioned with the gray area of his altruistic goals. He recruits several colleagues including Mr. Reese, Detectives Carter and Fusco, Shaw, and eventually Root who finds them.
Nothing is as it seems. When your think someone is a perpetrator, they may in fact be the victim. And vice versa. POI keeps it's viewership continuously guessing not only with who will survive to the season finale, how, and/or why, but keeps audiences questioning the true nature of right and wrong. And does the end truly justify the means?
There are constant thought provoking dilemmas that are almost applicable to realistic concepts. True, most of us aren't going to be required to shoot villans in the kneescaps in order to save a "number." But the ideal and question as to how far we should let government or a private entity violate our civil liberties in order to protect us from hostile organization is an issue pervasively struggle with.