Apparently more people than just me liked to too, because it spawned a sequel, Return from Witch Mountain. I remember reading the book, but I don't remember if I saw it as a kid or not. Well the sequel was on so I Tivo'd it, and it's pretty bad but still kind of fun for some reason. I couldn't help laughing every time I saw the description 'though:
Teens help two psychic children from another world thwart an evil scientist and his henchwoman.Sounds ridiculous, doesn't it? I suppose it is. The scary part is, it leaves things out, like the mind control device and telepathy with an heroic goat. But it gets better: The evil scientist is played by Christopher Lee and the henchwoman is Bette Davis. (How the mighty have fallen.)
Not that there aren't worse things, like "Afro Samurai" on Spike. I might have held on for a while if they hadn't included the evil gangsta cyborg monks.