Because of the terrible reviews at the time, the film might be worth seeking out.
It was also notable for its star, Mark Frechette, who turned out to be a loser much like Tom Neal (of Detour fame). Frechette ended up in prison and died in 1975 in a freak accident involving weights.
Here's a bit from the article:
The story is that in 1968 a bearded, down-and-out Frechette was spotted standing at a bus stop, shouting "motherfucker." Antonioni's aides, searching for a star for the film that was to be the director's American epic, interviewed Frechette and selected him for the role on the spot. "He's 20 and he hates," was their ever quotable comment. The film was a critical and financial failure, but it did bring brief fame to Frechette.
Frechette then took his costar Daria Halprin and the $60,000 he earned from Zabriskie Point and a few obscure foreign films and returned to the commune. Halprin eventually fled the reputed severity of the Lyman cult (and married actor Dennis Hopper*) but Frechette stayed put, out of the public eye, until two years ago when he joined two other Lyman devotees in an impulsive bank robbery attempted within blocks of the commune. One of his accomplices was killed by police and Frechette dropped his own revolver (with, it turned out, no bullet in the chamber).
Both Halprin, now 59, and Antonioni fared much better.
*--They were divorced in 1976, according to the IMDB. Hopper went on to marry two more times and is currently married to his fifth wife.