I thought this movie was alright being that it was my first time watching it. It's not anything like the horror movies of today because it obviously relies on an interesting story and creepiness; something Hollywood often does with special effects. This is just a creepy film and runs a bit slow at the beginning but it builds up towards an alright ending. Burnt Offerings is your typical "family buys/rents dream house at bargain price only to regret it" film. Obvious examples being "The Shining" and the "Amityville Horror," both based on books as well. There is also a strange person hidden away upstairs (c.f. Jane Eyre, The Old Dark House, The Ghoul (1975) etc).
The film is a study of family dysfunction, which is exacerbated by the haunted house (see also the first two films mentioned above). Issues explored include child beating, marital stress and breakdown, the importance/impotence of the father figure, and estrangement between all family members.
The most visible manifestation of the "evil" is the ability of the house to clean and repair itself. Unfortunately this is more of a householders dream than nightmare. No more breakages, tidying, "cowboy" building firms, etc. When Ben Rolf appears in a wheelchair, thus emulating Arnold Allardyce at the start, I thought the house was trying to "keep" rather than kill its occupants. The house needed a specific family imprisoned from which to draw its power/feed off. Thus the Alladyces were victims of the house. Their behavior at the start and motivation was of fear and escape. There lays their need to find a replacement family and sudden departure. However, the ending shows the couple to be in league with the evil, my initial impression being wrong.
The conclusion was too open-ended, the origins and mysteries of the house were not fully explained. Perhaps the source novel is clearer. The title, Burnt Offerings, seems a misnomer, nothing is burnt per se. The house itself was the offering; the family had high expectations, only to be fatally disappointed.