I read somewhere that Fisher's performance was "derided", but I really don't understand why. I am no fan of Fisher - if anything, I dislike him - but I thought he was perfectly adequate in this role. I really don't know what those critics saw in his performance that was so bad.
Most of those who derided Fisher's performance did so out of pique or ignorance. Many people were still angry about the Eddie, Debbie, Liz scandal and prone to insult him, and many others did not actually watch the film and made silly assumptions because Fisher was seen as 'Mr. Taylor'.
Actually in a movie with so much horrible overacting, his solid performance in a relatively small part may have been the best thing in the movie. Elizabeth was ashamed of her Oscar, and credited it to guilt over her health problems and being overlooked in prior years for much better performances.