An exciting piece of drama in its own right, "The Naked Time" helps define the Star Trek characters and establish what the series is all about in a way the previous episodes don't quite accomplish.
It begins by letting the audience in on what's happening (with a groovy sizzle sound effect), giving viewers an advantage over the Star Trek crew which must work to figure it out. It's the sci fi equivalent of Columbo, a show that eschews "Whodunnit?" (showing us the culprit at the beginning) in favor of "How's Columbo going to figure it out?". It's a risky choice because it can make the protagonists look stupid if they're too slow to figure things out, but like Columbo, Star Trek pulls it off well here, moving things ahead at a quick pace. The fact is that while the episode begins with the crew unknowingly discovering a new sickness, it's really about seeing the effects: a drug-like state that removes inhibitions, with consequences ranging from dramatic to comical. It's an opportunity for the normally professional crew members to give us a look at their true selves, laying a foundation of character development that will continue paying dividends for the cast for a quarter of a century, or in the case of Nimoy, fifty years. It's here that he finally nails the character, realizing that the trick to Spock is to have him try to hide his emotions while letting the audience in on the secret that he feels as much as anyone. It's a dynamic on display in one of Star Trek's most poignant and important early scenes, an uncut shot of the Vulcan breaking down in private as the camera rotates 180 degrees to catch the moment in its entirety. It's a beautiful piece of work which, as a precursor to the future, was directed by Nimoy himself.
Along with the emerging personalities of the Enterprise crew, "Naked" also establishes the tone of the series, from its dramatic opening tease ("It's like nothing we've dealt with before!") to the thrilling climax as the ship spirals downward toward the planet surface, the equivalent of a countdown clock. Future episodes would include more meaningful character conversations (with "Naked", due to its premise, including a lot of talking but little listening), but with its humor and spirit, not to mention an original musical score by Alexander Courage, this episode is a fine example of an early success for the series that it could build off of.
Curiously, the episode was originally supposed to end with a cliffhanger which would lead into "Tomorrow is Yesterday", but this is modified into more of a curious tag in the final version.
Remastered Edition: Some great little touches are spinkled throughout the episode, from a new establishing shot of the science station Spock and Tormolen visit in the opening, to a corrected Scotty phaser blast later on (which the effects crew forgot to put in the first time around). There's also a nice touch with the ship's chronometer, with the original inconsistent times replaced with correct times and a nicer looking display. The most notable change, however, is the planet itself, an upgrade that appears throughout the episode in establishing shots and on the viewscreen (with the latter putting the Enterprise in its proper decaying orbit as the ship spirals downward).