Okay, there might have been an element of "directed thrust" to it, but that's as far as the rocket analogy ever went. There was no propellant involved, there was no mention of exhaust, and the accelerations provided were physically impossible even for the ideal rocket.
The occasional mention of "fuel" in regard to the NCC-1701 aside, I suggest that a rocket engine capable of accelerating a spacecraft to relativistic velocities in a matter of seconds slots perfectly into a universe where supposedly alien species that evolved hundreds if not thousands of light-years apart can produce humanoid(?) females(?!) as hot - at least to this
20th/21st century human male - as Mea 3, T'Pring, Sayana, Eleen, Kara, Daras, Drusilla and Ilia, to name just a few.
What to make of the material in novels? Some, like Gene's novelization, describe a rocket; others, like Carey's Final Frontier, establish a field drive with similar finality. The latter makes more sense in terms of observed behavior and leaves more room for the impossibilities involved, but it remains as unaired as the former.
The salient difference being that both GR and JvP were, for better or worse, creatively involved with the production of ST:TMP
. Carey, thankfully, was not
. C'mon, FF
had DaddyKirk inadvertently capturing a Romulan admiral (or whatever he was - I haven't read it in decades) by "rescuing" what he thought was a Vulcan hostage, to say nothing of that ostensibly human Enterprise crewmember who - because he likes to eat dinner one section of his tray at a time - turns out to be a Romulan spy. I mean, seriously...