I don't know why - I always thought of this as the 'Christmas episode', and that has mostly to do with the snow in Hatfield Corners, VT, and Will wishing Davey and his aunt a merry Christmas.
When I first watched this show (I won't say when), I had a B&W television. It didn't 'bother' me (as people who never had b&w think it must be) - in fact, I'm someone who appreciates things which are (supposed to be) filmed and seen in black and white.
It gives a sense of separation between you, the viewer, and the story being told.
This episode is one of Billy Mumy's best during she show. He's someone far away from those he loves, but no one believes him, I guess it holds a pace near to me, because when I first saw it, I was about 6 or 7, and we all can remember what is like to be the 'little person', and have our thoughts and such not taken as seriously a we might wish.
But, in spite of his problems, and even though the Robinson's are having difficulties surviving back on Priplanus, it's where Will wants to be.
This episode is also one which doesn't focus on Dr Smith. It's truelly Will's story, and it also shows the beginnings of Howe much the robot will do to help Will (when Dr Smith's trying to get the robot to ignore what he's been told to do - by Will -instead of cooperating,the robot sends out high electric charges from both of his claws, in a sense saying, 'back off'.
If you've never seen this episode, and are just starting to watch this series, the first 2-3 episodes are a must, and the other 2 which automatically come to me are t beautiful, My Friend, Mr Nobody, and this. These episodes are the ones which clearly show how this show had the ability to become something special, rather than silly.
Enjoy.