Queen Elizabeth II (search) dedicated a fountain in honor of Princess Diana (search) on Tuesday and acknowledged that there had been difficult times with her late daughter-in-law but "memories mellow with the passing of the years."

The queen, her husband Prince Philip and Diana's former husband, Prince Charles (search), joined with Diana's family to formally open the $6.5 million oval granite water feature in Hyde Park.

It was the Spencer family's first public appearance with the royal family since Diana's funeral in 1997, when Earl Spencer criticized the royals for their treatment of his sister.

The queen acknowledged that Diana's death gripped the world's attention.

"Central to this remains the extraordinary effect Diana had on those around her," the queen said.

"Her drive to empathize with those in difficulty, hardship or distress, her willingness to embrace a new cause, her shrewd ability to size up all those she met, allowed her not only to touch people's lives but to change them."

On a personal note, the queen remarked that Diana "made such an impact on our lives."

"Of course there were difficult times, but memories mellow with the passing of the years.

"I remember especially the happiness she gave to my two grandsons," the queen said, referring to Princes William and Harry, who also attended the ceremony.

Construction of the fountain, designed by American architect Karen Gustafson and built of 545 blocks of Cornish granite, was delayed by bureaucratic wrangling and arguments within the Memorial Fountain Committee headed by Diana's friend Rosa Monckton.

The Royal Parks and the Department for Culture, Media and Sport provided extra funds when the installation ran $1.1 million over budget.

Mary Roach traveled from Whitley Bay in northeastern England for the ceremony but was unimpressed with the tribute to Diana.

"This is not a fountain. I'd have preferred to have had a nice fountain or a statue of Diana," said Roach, in her late fifties.

"You'll probably get rubbish thrown into it and it is really not that spectacular at all. It should be spectacular for Diana," she said.

"Some people have criticized the fountain but I think people will grow to like it in time," said John Loughery, 49, of London.

He said he camped overnight in the park to get a good spot. "I was the first one here. The reason is that Diana is a star in the sky," Loughery said.

Beate Henke, 46, of Espelkamp, Germany, said she was delighted by the memorial. "It's very simple and a good demonstration of Diana's life — a circle with ups and downs just like her life," Henke said.