I thought this was a fairly good episode.  Although it was intimated that there may have been a supernatural element, it alternately also intimated that there wasn't one.  I didn't see the ending coming (even though I heard it years ago) and I always consider a fiction character named Sybil to be evil (although I can't remember meeting anyone with that name in real life).  Marian Seldes' crying/hysterics can go over the top a lot, but it wasn't TOO bad this time.