Series It's okay
Perhaps it's just me, but Person of Interest is incredible predictable. Once you figured out the formula (which takes half of the pilot), it is pretty easy to foresee the twist of the week. Which wouldn't be too bad, if the characters were more engaging, but they are very much "paint by numbers", from the "soldier who morns his lost love" over the "scientist who did something he rues in his quest to better the world" over the "corrupt (male) cop" to the "good, hard working female cop", they all feel like they were picked up from some sort of retail store for standard characters to use in a show. And even that wouldn't be so bad if the characters were playing off each other better, but there is rarely a conflict, rarely a difference of opinion, and if there is, it is usually short and fleeting. The character development is choppy, too. There is a whole episode about Reese having "problems" to deal with domestic abuse, even though he took care of such a case before. Fusco's supposedly questionable character never really feels questionable at all.
The arc is a little bit better, especially since the recurring characters of the show tend to be way more compelling than the regular ones...but it is fraught with problems too. There are a little bit too many conspiracies, but even worse, they are just treated like a matter of fact. At this rate every second person living in NY is part of some sort of secret organisation.
In the current TV-Landscape, which is full of shows, especially crime shows, repeating the same plots again and again, it is one of the better shows, though. There are some flashes of brilliance, but they are few a far between. One can sit down at a quite evening and binge a couple of episodes without becoming too bored...but it's not a show which compels you to watch every episode, either. It is there, it is a good bet, but it doesn't stand out enough. And to be honest, the cavalier attitude towards privacy the show displays is a little bit off-putting.
Series Change We Can Believe In.
These days it is rare to see TV show-runners deliver on promises of "Game Changing" arcs or episodes where "nothing will ever be the same". It's also rare to see a series which has managed to pull off a Genre Shift successfully and remain intact. Person Of Interest has managed to do both. Its third Season for better or worse was willing to take drastic actions which would have made a TV executive faint from fear of lost ratings.
Starting as another quality CBS crime drama but with the unique twist of predicting and preventing violent crime, it's been a pleasure to see POI evolve over three seasons into one of the most relevant science fiction series in recent memory. From beating Ed Snowden in revealing the true scale of the US Intelligence communities surveillance efforts while giving all sides of the surveillance debate a fair hearing, to delving into the uncharted waters of artificial intelligence, POI has become one of the more topical and relevant dramas on network television.
While exploring topics such as cyberwarfare and the corruption of modern politics hasn't hurt, Season 3 of POI distinguished itself with masterful Character Development of the protagonists. From Taraji P Henson's Joss Carter deciding to finally drop the Conflict Ball when conducting a well executed Roaring Rampage of Revenge, her partner Kevin Chapman's Dirty Cop Lionel Fusco deciding to fight back against the men who made the previous 2 seasons a misery for him and Amy Acker's Root getting knocked down several pegs and rediscovering her humanity, the already formidable cast and writers threw POI's Team Machine into situations where they were forced to make critical choices and adapt like the show itself in order to survive.
Its detractors claim that it's become too complicated, the new characters are unlikable/smug/cold and that it should have stayed with the "case of the week format". I disagree. In the crowded CBS lineup consisting of shows such as NCIS LA and Hawaii Five-0, POI needed to find a way to stand out and define itself. By changing into a Post Cyber Punk drama albeit one based in a real world setting, it succeed in doing so.
Overall, by embracing change, POI has shown that it's destined for great things. We may not know what Season 4 will bring but it will most certainly be interesting.
Series Suspenseful and classy.
In a nutshell, Person of Interest is about a socially and physically isolated billionaire and a jaded ex-CIA operative who find purpose in their lives by stopping crimes before they happen. That is, with the help of a sapient supercomputer that technically isn't supposed to exist.
This show has all the elements of a good procedural: charismatic leads solving (or, rather, preventing) cases of the week, badass action scenes, and a long list of interesting villains. What really sets Person of Interest apart from the boatload of crime shows out there is the way it's executed. Rather than relying on the shock value of crimes to carry the story, it focuses on the situations that cause people to commit those crimes in the first place, and each episode delivers a new perspective to the usual victim-of-the-week format. The "person of interest" can in fact be either the perpetrator or the victim, whether they know it or not, and it is this ambiguity that makes for some amazing and suspenseful storytelling. See episodes like "Witness", "Number Crunch", and "Firewall" for examples of that.
There are also flashbacks employed in this series that reveal the motivations and personalities of Reese and Finch, as well as some of the people who shaped them to be who they are today. Some of them are truly heartbreaking. They all fit together with the case-by-case plot to present a more complex picture of how we got here, and we're slowly hooked with the story of the Machine's creation.
It's simple, really: as per its title, Person of Interest introduces us to some very interesting people, and the relationships between Reese, Finch, and their partners inside the NYPD (levelheaded Carter and conflicted Fusco, both with subplots of their own) take center stage. This means that even on the rare occasions when the weekly plot doesn't quite deliver, the characters and their interactions keep this show at the top of its class.
Series Does something Few Shows can, and does it Well
Person of Interest is a great show for a number of reasons: good acting (especially by Michael Emerson and Amy Acker), good writing, and well executed cinematography. All of that is more or less self evident if you watch any episode.
But more than that, Person of Interest makes a transformation roughly halfway through its run that very few shows can do in that it switches from a regularly procedural, "Plot of the Week" show, to a very serialized plot heavy show.
It also takes a more somber tone in general, around seasons 4 but manages to balance that with the character's (usually) indefatigable quippy nature-most of them, anyway-this actually increases over time, but (in my opinion) stops right short of being distracting. Shaw and Root are also two great characters who are (in Shaw's case) a positive example of someone with a mental disorder and (in both cases) positive examples of LGBTQ characters that aren't in-your-face about being queer characters as opposed to characters who are queer (which isn't something I actually have an issue with, but its something I see people talk about a lot, so if that's what you want, Po I has it).
The switch meanwhile, works, partly because it was built-up well, and partly because starting as a procedural and then going serial means the audience isn't totally thrown when we get a stand alone episode later on, and helped the writers "plug-in" stand alones to the overall plot.
In more general terms, Person of Interest was on the air at just the right time to get a number of really great performers for small, one episode roles (the kinds of people who could, and in many places do, be a series main or lead), which helps give all the episodes a very polished feeling.
Its not perfect TV (there is at least one recurring character who never quite "clicked", and while there are many plot points that pay off, a few are dropped), but its about as close as a mainstream, "good guys fighting bad guys, protecting the helpless" series can get.