The premise behind it was interesting ( like Alan Asherman, author of 'Star Trek Compendium',pointed about a brain running a planet. Gorgeous Marge Dusay and very comely Sheila Leighton both make excellent viewing.

Now to the ways it could have been better. We could have saw Kara beam over like we did. Then she beams back to her Ion propulsion vessel with unconscious Spock appearing on her transporter with his disembrained body lying down and his disembodied brain in a special metal box. Kara then orders a couple of the guys we see with her on the planet ( who are currently on her ship) over to the Enterprise to do some transporter sabotaging. Spock's disembrained body Kara has no further use for and literally empty-headed he too goes back to the Enterprise with those men.

McCoy and Kirk later have a conversation where they mention how recently they have learned to tie into the brain contrary to the backward technology the Federation possessed in ep 'The Menagerie'.

With their transporter deliberately broken they go to Kara's planet by shuttlecraft.

When Spock's telepathic emanations are first heard on the universal translator ( seen in Metamorphosis) it does not sound much like his voice. Then he quickly electronically adjusts his voice to come in on a communicator and sound like Mr. Spock ( as McCoy is uncertain the strange telepathic emanations are actually Spock's!).

Spock explains on the communicator that the planet only has one ship and it has been ordered away somewhere else far. Thus, they cannot put his brain back into his head the reverse way it was taken out.

In the climax McCoy gives a quick technological, scientific explanation for how Spocko never lost his well trained head of hair.