Annoying to the Older viewers in the audience due to the smarty-pants kiddie-character, but the Alien's ruthlessness makes for some scenes which are scary, maybe even disturbingly so.
The precocious boy's Mother is played by actress Marion Ross who would later play a Mother again in the tv-series "Happy Days." Surprisingly, it's the trivia of Marion Ross's appearance that somehow adds to the entertainment in that Marion Ross is so much associated with that other series "Happy Days."
A riveting scene is where the Alien's GILLS are exposed at the ending. This alien characteristic is what provides the mood of Eerieness. It would have been better if those GILLS had been shown earlier in the episode in addition to the ending. After all, it's Not his superpowers but rather his Gills which establish his extraterrestrial origin.