My understanding is that Andrew Lownie is a serious biographer, and I am sure he has made some effort to verify his sources' accounts, but as an initial reaction, some of the anecdotes verge on parody:
“Once playing golf in a group of four, Andrew hit an especially good shot on to the green. One of the other golfers said: ‘Good shot.’ The prince fired back instantly: ‘That’s good shot, sir, for you.’
If he walked into a room and people didn’t acknowledge his presence, he’s been known to clear his throat, say, ‘Let’s try that again’, leave the room and come back to make sure everybody stands, bows and curtseys.
[…]
Lucy, a former stylist who dated him, was surprised that when she offered to take him to the cinema and said she’d buy the tickets, he expected her to get all seven, to include his security.”
[...] maids [were] summoned from four floors below to open the curtains beside him. […]
‘Apparently his bedtime habits as a single man left a lot to be desired,’ she [Wendy Berry, the housekeeper at Highgrove whose son worked at Buckingham Palace] said. ‘A collection of scrunched-up, soiled tissues usually lay scattered around the bed each morning for staff to collect after they had made his bed.’
[...]
One day a train taking the duke to Birmingham was cancelled and he was told he could wait in the VIP lounge for the hour until the next one departed. He was furious […] He flicked his hand and shouted: ‘That train over there, for example, why can’t they divert that train to Birmingham?’”