In this episode we lose a character that seemed to generate a strong division between fans of the series, similar to the difference in feeling that was generated by the replacement of Dr Crusher with Dr Pulaski in season two. Was the death of the Tasha Yar character a good move for the show...when you consider the way in which the character seemed to undergo no personal development and how she went from having more major roles in stories that were poorly written (Code of Honor & The Naked Now) to having almost zero screen time in later episodes; the answer is definetly yes. By the time Skin Of Evil rolls around, Yar had become a totally useless and empty character that could easily have found good company among the Engineer Argyles of the ship. What it ultimately comes down to is that Denise Crosby was miscast into this doomed role of a character that simply had no chance to succeed in the role they developed for her. There is nothing that would have made a female head of security fail in and of itself but it was the presence of the Worf character, who in of himself just begs for attention and the fact that his nature is basically synonomous with security, that cause the Yar character to stick out as such a sore mismatch to the role she played.
As far as the story itself goes, it is reasonably well paced and developed. There is nothing ground breaking or that really grabs your mind but it was interesting to see a character that was so totally devoid of any good and so intrinsically evil. The physical manifestation of the creature is quite tacky and laughable at points (would be right at home in the 1960`s Outer Limits) but what it represents fits with the black encompassing form it took on. Highlight of the episode, definetly the death of Tasha Yar, especially if you watched it back when it first aired or had no idea that it was about to take place.