William said when Prince George was born on July 22, both he and Catherine, the Duchess of Cambridge, couldn't wait to show off their son.
"I'm just glad he wasn't screaming his head off the whole way through," he said during the CNN interview.
And while George is not even a month old, he said his personality is already shining through.
"He either reminds me of my brother or me when I was younger, I'm not sure, but he's doing very well at the moment. He's growing quite quickly actually. But he's a little fighter. He wriggles around quite a lot and he doesn't want to go to sleep that much," William said.
The second in line to the British throne talked about a range of child-rearing topics, from baby toys to diapers and sleep deprivation. And he acknowledged that his expert performance sliding his child's car seat into the back of the royal four-wheel drive outside a London hospital was a well-drilled exercise.
"Believe me, it wasn't my first time. And I know there's been speculation about that. I had to practice, I really did," he said.
The interview is part of a one-hour CNN documentary, "Prince William's Passion: New Hope, New Father," due to air on Sept. 15.
Meantime, the Duke and Duchess of Cambridge have released two new family photos. The pictures were taken by Kate's father, Michael Middleton, in the garden of the Middleton family home in Bucklebury, England. The first one shows the couple and their son. The second photo is all three of them with Tilly, the Middleton family pet, and Lupo, the couple's cocker spaniel.
The Associated Press contributed to this report.