I came across this book review, and wondered if any here share the writer's view (of the poet, not the book), or would care to offer rebuttal/opinions. I will put some quotes, but it's too long to put it all. Warning: the page does have ads, sorry.

In March 1959, at a dinner celebrating the 85th birthday of Robert Frost, the critic Lionel Trilling managed to accomplish something that few toast-masters in history have ever done: In his brief remarks, he permanently changed the way people think about his subject.
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Trilling recognized that the aged poet would not be helped in his passage to posterity by this Norman Rockwell carapace, which could only seem more fake and dated with the years. That is why Trilling insisted on calling Frost, to his face, "a terrifying poet." Really, he had less in common with Longfellow than with Sophocles, "who made plain ... the terrible things of human life."
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Yet if the "Notebooks" contain ore instead of ingots, for that very reason they seem to give us a glimpse of a more subterranean Frost. And the more private the poet, the more genuinely terrifying he becomes.
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Frost is known as a master of metaphor, and many of his poems take the form of extended metaphors. Yet when he writes, "I doubt if any thing is more related to another thing than it is to any third thing except as we make it," he shows how the power of metaphor can turn on the poet, plunging him into a world of sheer perspectivism where there is no essence, only likeness. If we can make anything resemble anything else, then we are doomed to perish from the very excess of significations.

This is the terror that has always loomed behind the willful optimism of the Emersonian tradition, and which Frost, very much like Nietzsche, was able to exhume from the corpse of Emerson's gentility. Perhaps not even Nietzsche ever captured that terror in an image as striking and bottomless as Frost's: "We get truth like a man trying to drink at a hydrant." At such moments, Frost's "Notebooks," like his best poems, remind us that there has never been a more genuinely mystical American writer.

subterranean Frost