Beyond the use of the Mirror Universe concept, though, to say that Mike Johnson's story is based on Jerome Bixby's 1967 teleplay is overstating the fact. The story is completely new, with Mirror Spock in command of the Enterprise (which bears more similarity to the refit Enterprise from the six original movies than to the ship from the 2009 film) in orbit of the Klingon homeworld. The Terran Empire's uniforms have gotten a redesign, which seem more sensible than threatening. Erfan Fajar's lines and the colors provided by Stellar Labs give the book a slightly different look than previous issues, but I quite like it; both Mirror Kirk and Mirror Spock have some really great, darkly shaded, maniacal facial expressions, and a certain warship I did not expect to see (but probably should've) looks almost alive.
It's the same solid storytelling readers have come to expect from this series over the last year, and though the handful of one-and-done stories from recent issues were nice, it's fun to return to these two-part takes on classic episodes. My gripe, though, is that the story deviates too much from "Mirror, Mirror;" while in that episode Kirk and several others went to the Mirror Universe, this is (so far, at least) just a story set in the Mirror Universe, with no intruders from the 2009 universe proper. The concept (and the plot, if I'm honest) is much more similar to the Star Trek: Enterprise episode "In a Mirror, Darkly," which took the same approach and came with a similar twist.
This is not a problem on its own, but I found it a bit disappointing; telling an alternate timeline story for an alternate timeline story feels almost redundant, and I was hoping for the extra excitement of pitting movie Kirk (or any of the movie characters) against Mirror Spock, especially given the movie relationship between Kirk and his Vulcan second-in-command. I suppose there is still time for that in the second half of the story, Star Trek #16, but the plot doesn't seem to be headed there.
This is a fun issue, and the art is a nice change without being a huge deviation from the norm, but I would be lying if I said that part of me won't dwell on what might have been.