Season 3 of True Detective is a very different kind of story from Seasons 1 and 2. Although people have been saying it's very close to Season 1, I disagree. While the environment, setting, and bureaucracy is similar to Season 1, you have to understand it's still a state police department in the South from the past. Not much is different about that kind of environment, so it makes sense the tones and cinematography are comparable to Season 1. But that's where the similarities end.
Minor Spoilers Ahead:
The story is quite different, and the focus of this season is memory. Human beings remember and misremember events of their lives, and that can come to define a person. I thought the frame of the story from the perspective of a man losing his memory was effective and quite a departure from Seasons 1 and 2. There really is no antihero here. These are just cops, and they're okay. Not superstars or geniuses, just guys doing a job. And that's what makes this season more realistic as a cop drama.
The conspiracy is also quite different from Seasons 1 and 2 with no real (I'll avoid ultimate spoilers here) evil at the end. There are bad people, sure, but it's not the level of true evil we saw in Season 1 or even the corruptibility of the villains in Season 2. I was surprised by the unveiling of the crime, it wasn't what I expected, and I think that's a good thing. They had to do something different for this season, strike a different chord, and I believe the show succeeded.
The very ending of the story is quite good, encompassing the entire frame of the season revolving a man losing his mind. It's poignant and real, and I was pleasantly surprised by that kind of semi-tragic ending.
Overall, I thought it as a good season and better than Season 2. Season 1 will still be the white whale any further seasons attempt to recreate, but maybe it can't be. This is still good television and much better than any cop drama out there.