Watching the premiere with 60's commercials for the first time really put the episode in a totally different perspective. My wife and I watched it like we never saw it before (she was so cute, "oooh, that captain is adorable!") and, as much as I always loved this episode, I can see why the cast and producers didn't want to lead off with this one. It's very slow moving, with long stretches of Nancy/Creature stalking in the corridors. Viewers walked away with a different view of the characters than Roddenberry et al seemed to want. Kirk is pretty cold once Crewman Darnell is killed; he is very sharp toward Nancy, bites McCoy's head off, has no patience for Crater, and simply won't listen to any arguments in favor of reasoning with the creature. And those arguments are good ones! There really wasn't a valid reason to kill it. Supply Crater with enough salt, send them both home. Done. But nope, once one of the men is killed, Kirk is a man on a mission. Further killings only serve to drive him harder. This isn't so bad seen a few weeks in, after we'd seen the lighter, more reasonable side of Kirk. However, this was the first time the general public is introduced to Kirk. Shatner is fabulous, but Kirk is too rigid and unbending.
Spock is also very cold and alien, but that works well. We're also made to believe the series will spend more time on the supporting cast.
What's weird is how everyone involved seemed to diss this one as a "monster" episode. It's really not. The creature's true form is seen for less than a minute of screen time. Until then, it's a horror/suspense piece with a shapeshifting alien. You want a "monster" show? Watch any 3rd season episode of Voyage to the Bottom of the Sea, where a roaring sea beast will spend a half hour crashing through the sub. This episode is far from it. Actually, the Salt Vampire, as we termed it so long ago, is the most sympathetic character in the story. Something that's usually lost on critics. However, my friend's 3 year old daughter totally got it.
A great way to celebrate the 50th. So much fun and illuminating to see it in it's original context.