Yeah, but coming from Dudley that's like "I love you.

I don't think you're a waste of space.

Aunt Petunia often said that Dudley looked like a baby angel — Harry often said that Dudley looked like a pig in a wig.

They think I'm a waste of space, actually, but I'm used to—"

"I don't think you're a waste of space."

If Harry had not seen Dudley's lips move, he might not have believed it. As it was, he stared at Dudley for several seconds before accepting that it must have been his cousin who had spoken; for one thing, Dudley had turned red. Harry was embarrassed and astonished himself.

How long have you been ‘Big D’ then?” said Harry.
“Shut it,” snarled Dudley, turning away again.
“Cool name,” said Harry, grinning and falling into step beside his cousin. “But you’ll always be Ickle Diddykins to me.”
“I said, SHUT IT!” said Dudley, whose ham-like hands had curled into fists.
“Don’t the boys know that’s what your mum calls you?”
“Shut your face.”
“You don’t tell her to shut her face. What about ‘popkin’ and ‘Dinky Diddydums,’ can I use them then?

But...surely you know where your nephew is going?' she asked, looking bewildered.
'Certainly we know,' said Vernon Dursley. 'He's off with some of your lot, isn't he?
Right, Dudley, let's get in the car, you heard the man, we're in a hurry.'
Again, Vernon Dursley marched as far as the front door, but Dudley did not follow.
'Off with some of our lot?'
Hestia looked outraged. Harry had met the attitude before: witches and wizards seemed stunned that his closest living family took so little interest in the famous Harry Potter.
'It's fine,' Harry assured her. 'It doesn't matter, honestly.'
'Doesn't matter?' repeated Hestia, her voice rising ominously.
'Don't these people realise what you've been through? What danger you are in? The unique position you hold in the hearts of the anti-Voldemort movement?
'Er - no, they don't,' said Harry. 'They think I'm a waste of space, actually, but I'm used to -'
'I don't think you're a waste of space.'
If Harry had not seen Dudley's lips move, he might not have believed it.