Season 3 is underrated but S4 and 5 are pretty much garbage. Theres a few decent episodes in there but overall the later seasons really do live up to their reputation of being abysmal television.

Arguably, the best episode of the entire series (Out Where The Buses Don't Run) was a Season 2 production and things tapered off from that point. The series itself was never consistent in its tone or quality and the third and fourth seasons simply made that apparent.
So, while there are good (even one or two exceptional) Season Three and Four episodes, they are far outnumbered by mediocre or poor ones.
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I remember at the time being taken aback by the change of tone in season two. And I missed a lot of the rough-and-ready cowboy tone of stuff like "Smuggler's Blues." Even so, some of my favorite episodes (like "Shadow in the Dark") are from later seasons and I really enjoyed the Sonny the Hitman storyline.
I also rewatched the series finale recently and was surprised to find I enjoyed it much more than I had when it first aired (because I wasn't thrilled to see it canceled at the time). I'd always loved that final montage to "Tell Me," but I was surprised that it was enjoyable as a solid TV movie and by that end-stage camaraderie between Crockett and Tubbs.
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I'd say the show was a bit more consistent in the first few seasons. The last couple seasons had some great episodes, but it was really hit or miss and when it was bad, it was bad.

Season one set a new tone for cop TV shows, but a lot of it was rough. Watch the first 3 seasons back to back and see.

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But wasn't the filmmaking at its peak in season one? I'm thinking now of episodes like Smugglers Blues, which were brilliantly directed.

Seasons 1 and 2 are pretty overrated- Season 2 especially because of the terrible acting with athletes and rock stars trying to be cool. Seems to me Season 2 is just a rehash of season 1 episodes, in fact.
Season 3 is the best because there isnt a bad episode in it and the guest stars were way cooler. Dont listen to the ones here that state S1-S2 are the best, they are not.
Season 4 is certainly flawed with some of the worst episodes ever, but there is enough good episodes to outweigh the bad ones.

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I dunno where/when that started. I've been watching this show since 2005, and even then, the idea of the first two seasons' superiority was widely disseminated. It feels like fans of the third season have become more vocal in recent years, but those two backend seasons still have that stigma.
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