1. USS Callister
Plot was very predictable, and dialogue was incredibly cheesy. I understand that may have been an intentional homage to shows like Star Trek but it ruined the drama of the episode.
2. Arkangel
By-the-numbers tale of helicopter parenting. Pretty much nothing important in this episode couldn't be done with today's technology; the filtering mechanic was completely wasted as setup for fairly vanilla teenage recklessness. Entire episode could have been avoided if any of the three main characters just had a discussion.
3. Crocodile
Difficult to sympathize with Mia or her family; luckily, Shazia and her family were very likable and were the reason this episode made my heart sink into my stomach. It's also a slow burner episode, takes a while for the first relevant tech to even appear, although once it gets started it starts to snowball fast--appropriate metaphor for the crimes she's committing. The shot of the water on the road lit up by the tail-light, making it look like a hidden trail of blood was a great visual metaphor. Ending seemed pretty nonsensical, and I would have preferred a more ambiguous conclusion.
4. Hang the DJ
Continues the trend of the best Black Mirror episodes being the simpler, mostly feel-good ones (e.g. Be Right Back, Nosedive, San Junipero). The mystery is always present but never dwelled on in favor of the relationship drama.The story implies the same type of events might transpire again, making the ending both sweet and sad, but it doesn't bluntly ask the question directly. The twist isn't hard to see coming but the emotional payoff isn't diminished. Also has a pretty soundtrack.
5. Metalhead
Tight script with tense pacing, wonderfully enhanced by the gory, dreary, monochromatic visuals. Unfortunately the ending reveal fails to provide a satisfying explanation of the world or motivations of the characters, and instead just causes further bewilderment.
6. Black Museum
Really did feel like a series finale. The internal mini-stories feel half-baked but are interesting enough, and they end up tying together with the main story pretty well. The conclusion has a celebratory tone that I think feels juvenile and undeserved as a completely unapologetic vindication of a revenge fantasy.
Overall, the 2-3 good episodes out of 6 for the season isn't great but isn't that far below the other seasons.