Haven't watched it. Always seemed like yet another procedural intended to give law-and-order conservatives (and other rah-rah-hooray-for-the-USA Republicans) a boner. Am I way off-base with this assessment?
It's the opposite of that. There are procedural elements yes, but everything gets tied together. The core idea of the show lets them do "monster of the week" style episodes, but the core mythology advances with each episode more than most serialized shows. The starts is a bit slow for two reasons. They likely were not sure what direction to take a few things, but mostly they were slowly planting ideas they would expand on later. And they expand on all of them. And not in a bulshitty way.
Once it gets going all episodes are different from the last, and expand on the story. I dont think any one character stays in the same place, or keeps the same mindset for more than a few episode before something logical happens to alter that and give them a new belief/drive to get something accomplished.
There is a computer in the show. I dont think that is a spoiler. The computer turns into a more compelling, layered, interesting character over the seasons than any living, breading, blooded character in many other shows.
The show is even smart with tech. They specially used a collection of old model PS3s in a episode cause only they could run Linux
It should also be noticed the the show focuses a lot of Global Surveillance, which is/was always a compelling topic, but not many people cared about it when the show began in 2011. Such topics became much bigger news in 2013 and later, so as the shows aired it managed to be topical with many of its themes.
I dont know what else to say other than the show is great. Has well developed characters. Has interesting themes running throughout, and it a great fun watch too.