The romance aspect is perfect. Season 3 got more emotional in general. Partly because we'd known these people long enough to grow to care about them deeply, Trek's makers and us alike. Partly it was the hiring of more female writers for season 3.
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I think the criticism of s3 is for two reasons: (1) legitimate sloppiness and bad writing, and (2) the more emotional tone. I think the former is a legitimate criticism (though there's a lot less of that than is generally thought), but not the second.
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Scotty is visibly in love. It happens. Even to the middle aged. You can even get visibly foolish, a little, though he doesn't really seem that way to me. I'm just happy for him, period. For Chrissakes, just be happy for Scotty.
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It's a good episode. It has always bothered me that we get no SF explanation for the survival of these beings. I was bothered by this for decades without putting my finger on the cause. It just seemed "hollow". I listened more closely lately, and it turns out the beings may just as well be literal ghosts. "We survived", that's all we get.
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Remastered spoils the element that makes the ep soar, the original effect of the Zetarians. It alarmed, stunned, it had horror and atmosphere. It was jarring and unexpected, alien. What they replaced it with was flashing brightly colored squares. Ooh, scary. So if you watched Remastered and decided you didn't like it, see the original.
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The #2 thing it has going for it is the romance. I usually have no interest in romance in stories, but this one really came alive. She wasn't just "the girlfriend" either, she had an interesting bit of orneriness to her.
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No one objected for one moment to saving the ship by almost killing her in a pressure tank...