It will haunt you!
Few ghost movies are this marketable, complete and polyvalent; containing taboos, scares and gore, yet available to adults and younger audiences alike. It is also convincing when relying on psychological horror. Ultimately, the fear of the unknown is what it focuses on. It makes you go through a wide range of emotions in between its terrifying key scenes, borrowing from many genres.
The cast is relatively limited. The actors are intense and can convey both humor and terror. The dialogue feels natural, when not purposely surreal. A character is injected late in the script to bring fantasy, spirituality and hope to a film otherwise much darker. The dynamic between scientists, believers and the family gives you a false sense of security that it can take away at any time.
The effects in Poltergeist sometimes reveal color key artifact, but the grain and technological limitations create a unique cinematographic signature. The major scenes are big and loud, and those flaws are soon forgiven, considering how much is thrown at the viewer. The directing, the editing and the score are an immersing torrent that truly adds to the ambiance.