I remember watching this when I was a kid. It scared the pants off me. Tobe Hooper happens to have directed Texas Chainsaw. It has the involvement of Spielberg I believe somewhere and ILM and I think the former was at odds with Hooper's dark vision! There is of course the tale of Hooper supposedly using real cadavers from a local mortuary / college for some of the end scenes.
The effects are amazing and ILM lends itself to the very spectral feel of them. But a lot of the poltergeist effects are highly practical and the music complements the direction by building emotion and a sense of dread which helps the audience really care about this normal American family.
The shocks are there. Its really creepy. And because we care and become invested in the family we really want them to be able to overcome their supernatural adversary.
It is not really for the 12A type audience more of a 12+ audience (don't say I didn't warn you). Don't even bother to see the 2015 remake. It is pantsy! The father's humour is misplaced and as a result you can't take anything that happens to the family seriously. Everything is better in the original: screenplay, direction, photography, sound, music, cast, characters, SFX, Practical effects, etc, etc
If you like engaging spooky thrillers you will not be disappointed. Don't forget the classics!