Chris Jackson/Getty Prince Charles
As the Prince of Wales, Charles became the longest-serving heir apparent in British history. Unlike his mother, who succeeded the throne at age 25 when her father died after a battle with lung cancer, the royal had plenty of time to prepare.
And with all that time in the royal "waiting room," he's had plenty of time to think about what kind of monarch he'll be.
King Charles III will be "very sincere," Kate Williams, history professor at England's Reading University and author of Young Elizabeth: The Making of the Queen, told PEOPLE.
"He cares about Britain," she said. "He really just wants to make it a better place."
However, King Charles will face a few issues on the throne from the get-go, Williams said. He's not nearly as popular with the British public as his mother was — or as heir Prince William and his wife Kate Middleton are — due to a less natural ability to connect with the public, according to Williams.
Danny Lawson - WPA Pool/Getty Prince Charles, Kate Middleton and Prince William
"He just isn't quite as popular," she added. "Whether or not making him King will change that, we'll have to see."
And he's not nearly as good as his mother was at keeping his political views close to the vest. In her 70 years on the throne, the Queen rarely made her own views public. Charles, who is a passionate environmental, less so.
"He has been accused of meddling politically, even though most of what he was doing was for good — most of the things he was asking for are things we'd support," Williams said. "But still, it's meddling." One example of this is the famed "Black Spider Memos," a series of letters from Charles to various government ministers. However, after the letters were published, public reception was fairly positive.
Charles will take on the heavy responsibility of the monarchy — a job for which he's been readying himself for decades. Though he's likely one of the best-ever prepared incoming monarchs in history (after all, he's taken on 500 or more engagements each year for more than a decade now), he'll still have his mother's legacy weighing heavily on his shoulders.
As Williams says, Queen Elizabeth has "raised the bar for any other monarch coming after her."