I think both S1 and 3 were as much (or more) about the protagonists, than the actual crime or mystery. In S1, both protagonist and story were exceptional. In S2, both were mediocre. In S3, I think the protagonists were great, the mystery/crime was a little above average. Casting really nailed it in S1 and 3, and shit the bed IMO in 2.
While I was a little disappointed in the mystery/story ending in S3, I love it how they left it with Purple figuring it out, but losing it, like he's losing himself. And I love that Dorff is moving in with the dogs.
Didn't really care for their shameless tie in to S1 (laptop image) which turned out to be meaningless to the story. Same with the documentary chick.
I just got around to watching last night, so it's still processing. Overall, the case wrapped too neatly. But I suppose the connection to S1 and documentarian made for an effective red herring even if it did play on our own desires as an audience for a particular outcome. I like the open-ended nature of whether Julie Purcell lived or not. Was it one last brilliant insight from a detective on his last legs or was it a writers desire for the power to choose her own satisfying ending?
I think the convo in the car with his daughter backs up the losing/finding of himself. When Hays asks if he lost her, it was clearly significant and deeper than the immediacy of his dementia. The lost and found aspect of Purple's humanity was profound. It hit home. From that lens, it makes the sequencing of the last episode near perfect.
Roland's transformation was less compelling but also less complete. His redemption is found in helping Hays at the end. In my opinion, the dogs and booze (which he appears to never lose as a crutch) represent comfort in the face of having killed a man, but in themselves, don't allow him to transcend the act.
I suppose that while we're left with loose ends, we have enough info to make some inferences. He pushed his daughter away in her teens/early 20s through the force of his personality. She finds it best for herself as a grown woman to keep significant distance from her father. Maybe there was a singular incident, maybe it the cumulative effect of years of an abrasive father. We can safely infer that Hays and his wife stay together until her death. They make the decision to let the Purcell case's central focus in their lives fall away (he leaves the force, she drops the second book).