His much-anticipated first outing as Hamlet may have found a sea of lacklustre reviews, but Benedict Cumberbatch has had at least one audience member jump to his defence – his mother, Wanda.

Speaking after the official press night at the Barbican, Wanda Ventham defied the critics to declare her son was “a bloody good Hamlet”.

Ventham said she and Cumberbatch’s father, Timothy Carlton, both also actors, were “extraordinarily proud”. She added: “He was quite lively growing up, but I thought that was phenomenal.”

As the fastest-selling show in London theatre history, the production, directed by Lyndsey Turner, had been subject to intense scrutiny in the buildup to the press night. But after all the excitement, Ventham’s glowing praise was in the minority.

It was a mixed bag of reviews, but many described the show as “patchy” and “flawed”. Much of the criticism focused on the staging and design. Cumberbatch appears in outfits such as a blue military jacket emblazoned with “King”, a David Bowie T-shirt and a hoodie.

The Guardian’s Michael Billington called it a dismal and frustrating production and awarded it just two stars.

He wrote: “He [Cumberbatch] is trapped inside an intellectual ragbag of a production by Lyndsey Turner that is full of half-baked ideas. Denmark, Hamlet tells us, is a prison. So too is this production.”

Benedict Cumberbatch as Hamlet. Photograph: Johan Persson/PA

Ben Brantley, the chief theatre critic for the New York Times said the show was “never emotionally moving” and added: “Some of the interpolations are seriously irritating.”

He continued: “This Hamlet seldom seems to relate to anyone else onstage. In the big dialogue scenes, you’re conscious of Mr Cumberbatch riding Shakespeare’s rushing words like a surfboard, as if saving his interior energy for the monologues.”

Meanwhile, Quentin Letts wrote in the Daily Mail that this was “a fine Hamlet in a patchy, occasionally puerile, production”.

Doubts about the quality of the production had already been raised by Times theatre critic Kate Maltby, who controversially reviewed the production during a preview show. While one of her major criticisms, that the “to be or not to be” soliloquy had been moved to the beginning of the production, was addressed by restoring it to its original place in act three by press night, she also criticised the lack of subtlety in Cumberbatch’s performance.

“This is Hamlet for kids raised on Moulin Rouge,” wrote Maltby, who also originally gave the show two stars. She offered an improved three stars for her press night followup, but called it a “gaudy and commercial production”.

The lukewarm response is likely to disappoint the legions of fans, many of whom are travelling from as far as Asia and America to see Cumberbatch play the Dane. Tickets for the production were being resold for around £1,500 online.