It seems everyone's got opinions!
A new book reveals Princes Charles, 68, wasn't too pleased with Kate and William during their first overseas trip as a married couple in 2011.
The Duke and Duchess of Cambridge, who were newlyweds at the time, charmed crowds from Calgary all the way to Los Angeles -- and the 10-day trip was well-documented by news outlets all over the world.
However, it's clear William's father had differing opinions of the major trip. According to Sally Bedell Smith's biography of the future king, Charles wasn't too happy about the couple's "tasteless" photo ops and was "more than a little irked" that they treated their work trip more like a personal vacation.
Kate and William made headlines on several occasions during the milestone trip.
The glowing newlyweds rocked cowboy hats when they were given the honor of pressing the button to launch the legendary Calgary Stampede.
Duchess Kate even had a Marilyn Monroe moment when her yellow Jenny Packham yellow dress was blown up by a gust of wind.
And we can't forget when William showed off his athletic prowess during a game of street hockey when they paid a visit to Yellowknife, the capital of Canada's vast Northwest Territories.
Though the royal trip was considered a success by everyone, Smith attributed Charles' disapproval to jealousy:
"Charles felt overshadowed by Diana and now it seems he feels overshadowed by their son. Some people may think he is jealous. I have always felt that as soon as William got married, Charles would feel sidelined."
These claims come as a surprise given Charles' lighthearted nature during official royal appearances. If you recall, he's known to bust a move and let loose. He recently kicked off a European tour by taking part in a traditional Romanian dance with the locals. You have to see it to believe it!
Prince Charles is set to take the throne once his mother, Queen Elizabeth II, passes. According to Smith, his son, Prince William, is being groomed to become king in his late 40s or early 50s (he is currently 34 years old).