You can argue that “The Man Trap” is just a monster story set in space — after all, that’s exactly what it is — but it’s easy to see how NBC and Desilu came to the decision to air it as the public’s introduction to Star Trek. The second pilot, “Where No Man Has Gone Before,” was deemed too exposition-heavy for the viewer’s first look at the Enterprise and her crew; the first episode shot, “The Corbomite Manuever,” was pushed back because the vast majority of its action takes place on the Enterprise, making it a bit claustrophobic as a first outing. “Mudd’s Women” was, well, “Mudd’s Women” and, weirdly, they thought “Charlie X” was “too gentle” because it featured an awkward teenager in the middle.  “The Naked Time” was also ready, but was delayed because it felt more appropriate to give the audience a chance to get to know the crew a bit before showing them going mad
The script for “The Man Trap” was penned by George Clayton Johnson, a noted science fiction author who had eight Twilight Zone episodes and multiple short stories (including one that would become Ocean’s 11) under his belt before he took on the task of writing one of Trek's introductory dozen teleplays. Multiple ideas were rejected in the earliest stages of scripting, including the episode title “Damsel With A Dulcimer” (?!?) and a tractor being used on the archaeological dig (eliminated because of budgeting and the need to shoot inside) but after that, Johnson's script zipped along fairly quickly into production. In The Star Trek Interview Book, Johnson says that John D.F. Black’s only real note of import on the teleplay’s first draft was that the M-113 creature should be onboard the Enterprise sooner, heightening the tension a bit.
(There may be a reason that “The Man Trap” was easy sailing for Johnson. he’d written a story called “All Of Us Are Dying” that was adapted by Rod Serling for The Twilight Zone episode entitled “The Four Of Us Are Dying.” The plot of that episode? A shape-shifter infiltrates a group of friends and turns them on one another.)
Despite some production wrinkles (especially with the sound — when Kirk calls out “Crewman Green!” on M113, the echoes definitely sound like they’re shooting the show on a sound stage)  there’s a lot to like about the way “The Man Trap” looks and feels. The lighting, like many episodes from the first batch, is moody and well-chosen. There’s a lot of care given to shot composition and the budget is used very well, even when it’s plain that Sulu’s pet plant Beauregard is puppeteer Bob Baker’s hand in a very brightly-colored plastic glove and that the alien creature’s face is a gas mask modified by Wah Chang and his fellow craftsman.
It’s obvious from the very beginning that Star Trek was a very different sort of show for the time. The characters weren’t great adventurers on a noble quest: they were people doing a job in space. In the first few minutes, Dr. McCoy is introduced as an older gentleman, someone who’d had a life previous to joining the Enterprise, immediately showing much more depth than other science fiction series of the time (especially Irwin Allen’s productions) would dare impart to their characters. Sure, “The Twilight Zone” and “The Outer Limits” were science fiction anthologies for the Playboy set, but the first scenes of “The Man Trap” told a broad audience that Star Trek was going to be a series that treated its characters and setting well. Sure, it all seems a bit quaint and clumsy now, but it was a huge step forward for writing for series television, especially in the genre.
Not everyone thought “The Man Trap” was a good start to the show. Variety’s review of the episode was brutal:“Star Trek obviously solicits all-out suspension of disbelief but it won’t work. It was an incredible mess of dreary complexities and confusion at the kick-off… By a generous stretch of the imagination it could lure a small coterie of the smallfry, though not happily time slotted in that direction. It’s better suited to the Saturday morning kidvid bloc.”
The same piece also described Shatner and Nimoy as “wooden” despite “working hard to appear credible” before stating that ultimately, the episode was “dreary and confusing.” I can legitimately understand the former: it’s a strangely muted affair, even with the brightly colored uniforms and bits of humor. However, the latter of seems an odd complaint considering how straightforward the actual episode is. Maybe it’s proof that Star Trek was ahead of its time. Or, at least, ahead of one critic for an entertainment newspaper given to creating nouns, verbs and adjectives out of whole cloth.
TV Guide agreed with the assertation, saying that “the sky’s not the limit for this Trek" in a moment that I’m sure led to one writer going around the office demanding high-fives from his compatriots. (Of course, TV Guide would change its editorial tune over the years, publishing dozens of Star Trek-related covers thanks to the original series, films and spinoffs.)
Is “The Man Trap” one of Star Trek's best episodes? Not by a long shot. At the same time, however, it serves as a useful example of how quickly its voice asserted itself and how committed its cast and crew were to presenting good, smart  television that celebrated certain tropes while elevating the genre.

You can argue that “The Man Trap” is just a monster story set in space — after all, that’s exactly what it is — but it’s easy to see how NBC and Desilu came to the decision to air it as the public’s introduction to Star Trek. The second pilot, “Where No Man Has Gone Before,” was deemed too exposition-heavy for the viewer’s first look at the Enterprise and her crew; the first episode shot, “The Corbomite Manuever,” was pushed back because the vast majority of its action takes place on the Enterprise, making it a bit claustrophobic as a first outing. “Mudd’s Women” was, well, “Mudd’s Women” and, weirdly, they thought “Charlie X” was “too gentle” because it featured an awkward teenager in the middle. “The Naked Time” was also ready, but was delayed because it felt more appropriate to give the audience a chance to get to know the crew a bit before showing them going mad

The script for “The Man Trap” was penned by George Clayton Johnson, a noted science fiction author who had eight Twilight Zone episodes and multiple short stories (including one that would become Ocean’s 11) under his belt before he took on the task of writing one of Trek's introductory dozen teleplays. Multiple ideas were rejected in the earliest stages of scripting, including the episode title “Damsel With A Dulcimer” (?!?) and a tractor being used on the archaeological dig (eliminated because of budgeting and the need to shoot inside) but after that, Johnson's script zipped along fairly quickly into production. In The Star Trek Interview Book, Johnson says that John D.F. Black’s only real note of import on the teleplay’s first draft was that the M-113 creature should be onboard the Enterprise sooner, heightening the tension a bit.

(There may be a reason that “The Man Trap” was easy sailing for Johnson. he’d written a story called “All Of Us Are Dying” that was adapted by Rod Serling for The Twilight Zone episode entitled “The Four Of Us Are Dying.” The plot of that episode? A shape-shifter infiltrates a group of friends and turns them on one another.)

Despite some production wrinkles (especially with the sound — when Kirk calls out “Crewman Green!” on M113, the echoes definitely sound like they’re shooting the show on a sound stage)  there’s a lot to like about the way “The Man Trap” looks and feels. The lighting, like many episodes from the first batch, is moody and well-chosen. There’s a lot of care given to shot composition and the budget is used very well, even when it’s plain that Sulu’s pet plant Beauregard is puppeteer Bob Baker’s hand in a very brightly-colored plastic glove and that the alien creature’s face is a gas mask modified by Wah Chang and his fellow craftsman.

It’s obvious from the very beginning that Star Trek was a very different sort of show for the time. The characters weren’t great adventurers on a noble quest: they were people doing a job in space. In the first few minutes, Dr. McCoy is introduced as an older gentleman, someone who’d had a life previous to joining the Enterprise, immediately showing much more depth than other science fiction series of the time (especially Irwin Allen’s productions) would dare impart to their characters. Sure, “The Twilight Zone” and “The Outer Limits” were science fiction anthologies for the Playboy set, but the first scenes of “The Man Trap” told a broad audience that Star Trek was going to be a series that treated its characters and setting well. Sure, it all seems a bit quaint and clumsy now, but it was a huge step forward for writing for series television, especially in the genre.

Not everyone thought “The Man Trap” was a good start to the show. Variety’s review of the episode was brutal:

Star Trek obviously solicits all-out suspension of disbelief but it won’t work. It was an incredible mess of dreary complexities and confusion at the kick-off… By a generous stretch of the imagination it could lure a small coterie of the smallfry, though not happily time slotted in that direction. It’s better suited to the Saturday morning kidvid bloc.”

The same piece also described Shatner and Nimoy as “wooden” despite “working hard to appear credible” before stating that ultimately, the episode was “dreary and confusing.” I can legitimately understand the former: it’s a strangely muted affair, even with the brightly colored uniforms and bits of humor. However, the latter of seems an odd complaint considering how straightforward the actual episode is. Maybe it’s proof that Star Trek was ahead of its time. Or, at least, ahead of one critic for an entertainment newspaper given to creating nouns, verbs and adjectives out of whole cloth.

TV Guide agreed with the assertation, saying that “the sky’s not the limit for this Trek" in a moment that I’m sure led to one writer going around the office demanding high-fives from his compatriots. (Of course, TV Guide would change its editorial tune over the years, publishing dozens of Star Trek-related covers thanks to the original series, films and spinoffs.)

Is “The Man Trap” one of Star Trek's best episodes? Not by a long shot. At the same time, however, it serves as a useful example of how quickly its voice asserted itself and how committed its cast and crew were to presenting good, smart television that celebrated certain tropes while elevating the genre.