Amongst this growing crowd of architectural ephemera, The Serpentine pavilion is the heavyweight contender - the first, biggest and most consistent of these temporary projects. The Serpentine sits alongside annual cultural events like the Turbine Hall installations. And to underline its stature, it's back with the biggest architect on the planet.

Gehrys pavilion is big, chunky and confident - a wonky, open sided, breezy structure that's somewhere between landscape and architecture. It sits in Kensington gardens like a cubist copse. Cyclopean chunks of wood form the pavilions posts that recall the trunks of abstract Sequoias. They've been thrown together in an improbable framework. Layers of glazed rhomboid frames hang high up above you like a forest canopy from a branchy network of steels. Underneath, it's like being in a clearing. More super sized lumber forms stepped bleachers - piled up like a wood yard. Around the perimeter are shacks and stairs, sharply rendered in plywood. It creates a space that's a kind of Canadio-Californian fantasy: lumber turned into a woodsy, let-it-all-hang-out culture.

But for all its wonky geometry, the pavilion forms a surprisingly respectful axial porch framing the portico of the gallery. You can slip smoothly though it - splat, into what might look like the entrance to the Serpentine gallery if you'd only ever seen drawings and photographs.

Most weirdly, it feels like a giant model - as though through some freakish accident we've been shrunk to the size of 1:100 plastic people. The timber posts and beams seemingly lock into each like a giant replica of modelshop balsa handiwork. The way one stick joins to another has been blown up into a gargantuan simulated detail. The model-replica sensation makes me look up, almost expecting to see a giant globule of UHU frozen mid drip above my head.

If anything, here it's all been too well resolved. You can feel the hand of an executive architect faithfully reproducing the models intent, but somehow missing its point, as though something, somewhere got lost in translation. Frustratingly, it doesn't quite live out its vernacular-adhocist possibilities. The improvisational form becomes more standardised as you zoom in.

Gehrys work is much too relaxed to be hung up on the anal moralities of construction which obsess British architects. While the pavilion seems a return to Gehrys 1980s interests - what you might call high-low-tech - the same ad hoc spirit runs unnoticed through many more recent projects. Beyond the photographs, despite the Titanium, it's still often thrown together, bolted up in such a way as to recall vernaculars, the loose binding of sculpture and a resistance to detailing. It's never quite seemed a comfortable fit with his role of figurehead to the perfect abstraction of the digital shape-makers. This reading suppresses other potential (more rewarding) links to varied architectural trajectories which might bracket postmodernism with nouvaux-vernacularists like Atelier Bow Wow.

The pavilion seems to collide a range of diverse architectural modes. There's a sense of picturesque landscape design where groups of trees were used to define space and view - reflecting its Kensington Gardens setting. It draws on the glee and improvisation of building a tree house (and like many-a treehouse, this is the result of a father-son collaboration). But there is also a certain stiffness, perhaps echoing the Victorian grandeur of South Ken in its monumental scale and formal relationship with the gallery.

The pavilions posts and beams dramatise a balancing act of construction, but the balancing of the pavilions feel proves trickier. It's as though its not quite sure how to resolve its boho vibe with Albertopolis. Its aspiration hints at a new kind of monumentality - one where the Albert Memorial might be resculpted with the Prince Consort sporting a pair of gold-leafed Levis, a caffeine free diet coke, and an iPod.

First Published in the Architects Journal