With one viewing, I would have agreed that this movie should never have been produced. Then I went back and watched it again (I'm a pervert), and damn! What seemed at first like painful drivel, now made much more sense. The sequencing is unfortunate; Helena's symbolic importance is obscured until the end, at which point it's overshadowed by the cheesy "but then he woke up" device. The parallels between Helena and Dr. Nick's mother should have been better accentuated as well.
Armed with foreknowledge of the dream sequence as such, this movie is reshaped as a disturbing story of a man's sexual inadequacy, heavily laced with Oedipal and castration symbolism. Dr. Nick is obsessed with Helena because she is so like Mother (and the limbless statue): beautiful, sexually appealing, but providing no emotional nourishment. Young Nick didn't get much positive attention from Mother; note the dialogue in the opening party scene: "oh, she didn't mention having any children." Throughout the rest of the movie, Mother is always portrayed as angry or contemptuous. Dr. Nick doesn't love Helena (despite shifty-eyed dialogue to the contrary); he just wants to rewrite his relationship with Mother.
In flashback, when he takes ownership of the family estate, he recalls one of Mother's lovers leaving her bedroom. Mother struts out and sneers, "You were watching me, weren't you." Dr. Nick jogs by Helena's house, and climbs a tree to peep into her window. Dream-Helena derides Dr. Nick for his premature ejaculation with Anne, then points back to his ineptitude in their own one-night stand. These scenes establish Dr. Nick's sexual inadequacy. Anne's reassurances don't help him feel more virile; on some level he senses that he's losing something important by letting Anne gloss over his sexual dysfunction. In this respect, dream-Helena is a tough inner guide, forcing Dr. Nick to face up to his inadequacy.
The whole extended dream sequence, then, is Dr. Nick resolving his love-hunger in an imaginary world where he (literally) has the object of his desire, and the price of that sort of "having": secrecy, shame, loss of his surgical career, loss of Anne's real uncoerced love, fear of Helena's rescue, and the grotesqueness of this ultimate objectification.