A scene showing Downton character Mrs Patmore in rapture at the performance was "scarcely convincing", Christiansen said.
The more realistic reaction came from maid Anna Bates, who "whisperingly complained of a headache", he said.
Christiansen was also sharply critical of Dame Kiri's acting.
He said her lines were "stiffly parroted and nervous"
They reminded him that "even in her glorious vocal prime she had never been much of an actress".
"I greatly admire the shrewd casting of Downton Abbey, but this was not one of its happier inspirations."
Dame Kiri has previously spoken of how thrilled she was to be invited to perform on Downton.
"I nearly choked when I saw the email that invited me," she said.
She named her dog "Abbey" to celebrate her role on the hit show.
"It was a long day but I made it longer by staying up most of the night," she said.
"The most incredible thing is I took my two dogs along and Lady Carnarvon didn't want those anywhere near the place but the thing is during the time I was expecting doggy number three and she's called Abbey as in Downton.
"She's my little Downton prize."
Season 3 of Downton Abbey is set in 1922 and sees the characters dealing with the death of Matthew Crawley (Dan Stevens).
- nzherald.co.nz
