The New York Times critic, Ben Brantly, called the show "largely incomprehensible," while Richard Ouzounian of the Toronto Star noted he was "bored of the Rings."
Reviews by British critics were less scathing, the Times of London reported, with The Guardian's reviewer calling the production "intelligent, but not satisfying."
Specific remarks included orcs who looked "less like brutal mercenaries than clumsy backup singers," according to Time. Variety called it a "saga of short people burdened by power jewelry."
Despite critics, the 3 1/2-hour show, featuring 55 actors, won Canadian theater awards. Lyricist Shaun McKenna was awarded a Dora. Director Matthew Warchus won for outstanding new musical and Michael Therriault was honored for his performance as Gollum.
"Frankly, I believe that if the same critics had seen it at the National Theatre in London, they would have embraced it," said Kevin Wallace, its British producer.
A reworked, shorter show will open in London next May 9 at the Theatre Royal Drury Lane.