The opening-night queues for Damien Hirst's exhibition at the Serpentine Gallery snaked out on to the pristine grass of Kensington Gardens. A consummate collector with a fortune worth more than £100m, Hirst has acquired an artistic treasure trove in the course of his career. He has also amassed hordes of hangers-on: groomed and glistening models and celebrities, paparazzi and press, curators and admirers. This time, they had gathered not to admire Hirst's own work, but to see his "Murderme" art collection, appropriately named after one of his bank accounts.
Hirst started collecting 15 years ago, exchanging works with his friends Tracey Emin, Angus Fairhurst and Sarah Lucas. Since those days he has expanded it with his wealth, and it includes works by his A-list "heroes", such as Francis Bacon, Jeff Koons and Andy Warhol. Hirst has even started to buy back his own work, in what he calls "[showing] confidence in your own product". But he has chosen not to include this in the exhibition, allowing others of his generation - particularly Lucas, whose pithy one-liners punctuate the show - to shine.
Work by a number of younger artists, many of them among the dozens of assistants Hirst employs in his studio, prevents the exhibition from degenerating to the box-ticking predict ability of corporate art collections. The best is Tom Ormond, with Cluster Cottage, an unsettling reworking of the traditional English landscape genre, in which a thatched lakeside idyll is disturbed by acid-toned, space-age invaders. Other high points come with some unexpected juxtapositions and canny placements: Lucas's stark blue-neon coffin is paired with Angela Bulloch's mesmeric light-box modules, and Koons's joyous Moon (Yellow), an oversized helium balloon fashioned from steel, engages brilliantly with the gallery's classic central rotunda.
And yet, disappointingly, Hirst's curatorial acumen is little in evidence here. He has a history of pioneering exhibition-making behind him, notably the provocative "Freeze", which he presented in 1988 while still studying at Goldsmiths College. For the Serpentine show, he spent months planning the hang, with a scale model of the gallery sitting next to him in his studio. But his personal investment in the show - he acted as buyer, selector and curator, as well as commissioner of a series of limited-edition prints and publisher-editor of the exhibition catalogue - gives rise to certain tensions and inconsistencies. As a collector, he has crammed far too much of the work into the space. Trusting his artist's eye, he has decided not to place labels within view of the actual pieces. But the series of minuscule captions at floor level is near impossible to read, and when you do bend down to see them, the descriptions fail to specify what materials the works are made from (often a fascinating clue to their meaning). While some of the connections between works are well made, others are glib or trite: an orange painting by Francis Bacon is placed next to an orange painting by Richard Prince.
Visitors will not come to this exhibition to see contemporary art, however: they can do that any day at Tate Modern. The draw is what it tells us about Damien Hirst himself. His preference is, unsurprisingly, for work that displays the same hard-hitting wit and sense of the grotesque as his own does. Many pieces tackle his favourite subjects, from sex and death to mass media and popular culture.
More interestingly, the collection gives an insight into his acquisitive obsession, of which this show represents the tip of the iceberg. Hirst describes collecting as an addiction and sees it as the core of human existence: "As a human being, as you go through life, you just do collect. It was that sort of entropic collecting that I found myself interested in - just amassing stuff while you're alive. It's like stuff washed up on a beach somewhere, and that somewhere is you."
Besides fine art, Hirst has bought huge volumes of highly diverse and idiosyncratic objects: more than 200 fake Picassos, which he buys on eBay and incorporates into his oeuvre by signing them himself, and curiosities in the 18th-century tradition, such as cows with six legs and the bullet-scarred skulls of assassination victims. He is photographing all of London's pharmacies to create a whimsical portrait of the city, which he intends to chronicle in a book. All of this flotsam and jetsam will be housed in the artist's new Cotswolds retreat, the Victorian Gothic Toddington Manor, where the full extent of his collections will go on view to the public in a few years' time.
While all this energy and ambition is admir able, there is a risk that the whirligig of activity is distracting him from his own work. Hirst urgently needs to reinvigorate his practice, after harsh criticism of recent shows in New York and London. But is he doing so? The catalogue interview with Hans Ulrich Obrist gives a glimpse of his chaotic world. Hirst admits to undergoing something of a mid-life crisis, as he reaches a major point of transition. He speaks tellingly of his fear of the blank canvas, in front of which "I get no ideas, I get stuck".
Yet the truth is that Hirst is at his best and his most compelling not when he is being a property magnate or restaurateur or pop star, nor even when he dons the curatorial cap, but rather when he is making art: provocative, timely, profound pieces that engage us and ask us to rethink our attitudes to the world. Only by squaring up to the blank canvas will he prevent the Murderme collection from bringing about the death of his own creativity.
"In the Darkest Hour There May Be Light: works from Damien Hirst's Murderme collection" is at the Serpentine Gallery, London W2, until 28 January 2007. www.serpentinegallery.org 
Jacky Klein is an exhibitions curator at the Hayward Gallery in London