I agree.
To answer the OP, I think he's doing well under a massive pile of rotten luck (difficult family issues, cancer, score-settling by nasty ex BIL).
But Elizabeth II came to the throne as a 26 year old - attractive - woman. She represented something Charles can never replicate: a sense of 'the war has been won, a new age is dawning, Britain is booming and things are going to be better for everyone'. She became in many people's minds the personification of that post-war mood. Also (and I know some pps will scoff ) she was glamorous in her youth.
Charles was an elderly man when he took the throne and had already weathered some gruelling scandals, as well as the tragic death of Diana. He was neither young nor glamorous and the UK is very far from that hopeful, forward-looking country it was in 1952 (ooh - forget the Everest climb too, which cheered everyone up then!).
So it's just not a fair comparison. I don't think KC expects ever to be able to emulate or equal his mother's reign but I think he's doing OK in difficult circs. And I've been impressed by what I've seen of his soft diplomacy too - esp on the US visit. My God, that would have been a minefield - but he played a blinder.
And he was brilliant in the way he kindly and sympathetically welcomed Zelensky, too, after Z had been coarsely insulted at the White House by those rednecks Trump and Vance. He showed how a proper HoS deals with another.