I'll begin at the end, with the end credits sequence. In most shows, this is just a bunch of boring black screens or a scrolling text. Not in Trek, that's for sure. We have a whole bunch of images designed (and quite successfully I might add) to whet our appetite for upcoming episodes; some of these, which vary from week to week, are rightly considered iconic.
In this episode, the crew come across a communications pod from a long-lost vessel (my first thought - "it's a garbage pod!") and upon entering a pink swirly thing in space, one of their crew, an old Academy colleague of gets funny eyes and strange powers.
(I decided to look up the two guest stars after seeing that Gary Lockwood's name sounds familiar. I've not really heard of him, but Sally Kellerman is best known for her role in MASH, where she played "Hot Lips")
We get to see Kirk having to face the difficult decision of basically killing a long-term friend of his and the climax sees not only him get his top ripped (this episode, oddly does not feature Uhura or the mini-dresses), but also chew the scenery. Parodies of Kirk usually focus on this last part, but Kirk is a complex and multi-layered character.
It also marks the debut appearance of two other staples of the franchise - Scotty and Sulu. I will say that I have problems understanding Scotty - and I used to watch Taggart.
Another highly entertaining episode, but it does drag a bit nearer the end.