This is not a good movie.
Despite an interesting filmmaker and a fun lead, it's difficult getting through this one in a single sitting.
It is, however of interest as probably the first demonic television set movie, a genre that would go on to include Poltergeist, Videodrome, and many less memorable efforts. Though the Twonky was not released until 1953, it was completed in '51, just four or five years after television became a national medium.
Particularly when you take into account the rollout schedule of stations, the speed with which TV became one of, if not the, dominant cultural and political force, and one of the dominant economic forces in the country is astounding. The revolution did not go unnoticed at the time. Writers and cultural critics penned any number of alarmist essays and stories. I suspect that no medium before or since has created quite as intense a feeling of anxiety.