Scott Rothkopf, curator of the Whitney museum and co-curator of Jeff Koons: A Retrospective at the Guggenheim Bilbao, says he remembers an 'embarrassing' photo of himself in shorts and sandals taken years ago in front of Puppy, Koons' giant floral canine on the Bilbao waterfront. And who hasn't, on a summer city break, been snapped doing jazz hands beside Puppy or Balloon Dog or Popeye?

Yet few of us, Rothkopf included, might have predicted these larger-than-life statuettes would gain widespread critical in our time. Or that Koons would transcend to international treasure from the artist who cost too much, partied too much and shared way too much.

At least that is what this monumental show - third in a travelling suite that included the Whitney Museum of Art and the Centre George Pompidou - seems to suggest.

The sheer scope of the exhibition - from the artist's heady early days down, quite literally via spiral staircase, to his more recent work on the main floor - illustrates an artist constantly working, thinking, pushing, tempting. His is the classic short man's desire to bring people together in a so-called 'Dionysian festival' of viewership.

Frank Gehry's multifaceted Guggenheim building is the venue for it. As Koons said ahead of the opening on Monday, 'I've never seen my work look more elegant than here. Within this architecture the works take on a comfortable aspect.' You could hardly disagree.

Over more than a year on tour, Koons, has had time to reflect on his four decades exploring new and expressive forms in art. He speaks like a man who is at peace with his message and medium, spouting affirmations like a proper 12-stepper drinking the Jeff Koons Kool-Aid. 'Once you have self-acceptance,' he says, 'you reach a higher stage of acceptance of others. Trust in yourself in order to achieve your potential.' If he's had any weakness, 'it's been not accessing my highest state of consciousness.'

The overarching theme of Jeff Koons: A Retrospective is reflection - of the self and the environment. From an early age accompanying his father to the family's interior decoration store, Koons has thought about the power of reflection to affect how we feel. His most effective works use the power of reflection to entice, then invite further reflection on our feelings of love and disdain, internal and external, luxury and kitsch, modernism and the Baroque.

The latest works pair gargantuan plaster casts with mirrored blue 'gazing balls', ornaments that enjoyed popularity in the 1500s before popping up again in the residential gardens of America. 'They have a generosity that reflects you, affirms you,' says Koons.

Rothkopf announces a 'surprise' through every doorway in Gehry's unpredictable building. No surprises here, just the inexorable quest for perfection, the desire to please, what Rothkopf rightly calls 'the finger-in-socket, sugar-jolt of pop art'.

At 60, Koons is back at work, investigating new and expressive forms in marble and granite. He's not close to being done, retrospective or no. I'm with Rothkopf when he says, 'I look forward to the sequel.'