I agree with pretty much everything that's been said so far. IMHO, "The Alternative Factor" is the only truly bad episode of TOS's first season. It was obviously extremely rushed in production and probably in writing as well. Those repeated spinning starfields and stuntmen fighting in dry-ice fog just scream "padding." And the wonky science is even wonkier than the usual level of wonk in Trek science.
At the time, though, I thought Lazarus's little one-man ship was kind of cool-looking. Pity it was missing a door!