Nigel Martin-Smith put Take That together in the 1990s but reckons Gary's new show needs to be more critical.
The series is on the hunt for five male performers for a new musical based on the songs of Take That.
But in an interview with The Sun newspaper, Nigel said: "I think artists are naturally supportive of other artists because they know what’s it’s like.
“But the viewer doesn’t care, sat at home watching it saying ‘that’s bloody awful why is everyone saying they were good?’"
Let It Shine started with over 6 million viewers earlier this month but dropped 500,000 in just one-week.
"I think the show is fantastic. I think for what it is it’s very clever because Gary’s not setting out to find the next Take That," Nigel continued. “But if you look at those sorts of shows the ones that do well you’ve got Simon Cowell being critical, ditto BGT, and Strictly you’ve got Craig Revel Horwood.
“They’re almost like a panto with the villain being the baddy, but also I think you’ve got to have someone being honest.
“I think they need that really and it’s the only thing that doesn’t work for me.”
Let It Shine continues tonight at 7PM on BBC One with the latest round of auditions.