Critical reception of the architecture of the London 2012 Olympic Games has been characterised by bipolar waves of great disappointment, followed, some months later, by bursts of cheerful optimism.

In keeping with our national character, most of the venues were subject to a torrent of acerbic criticism when their designs were first unveiled in the press. The main stadium, by mega-entertainment infrastructure specialist Populous, was variously accused of being "wilfully lacklustre" and "like something from Ikea, fit for a garden party," when images of its modest white frame were first published. Gone were the dynamic sinews of Foreign Office Architects' bid-winning scheme, which had risen from the winding waves of their park like an alien creature, taught with the energy of rippling muscles. Instead, glowing in a rendered mist of beige, this looked more like a stunted gasometer, a dreary vision in Meccano-lite.

Yet, now finished, it has been hailed as the lightest ever stadium of its kind, a model of pared-back, efficient structural design. Its minimal frame marches elegantly around a lean seating bowl, with all ancillary functions either swept beneath its podium, or housed in temporary pod-like structures around the site. It is a fitting monument to our provisional, flat-pack, austerity Olympics.

The aquatics centre, by Zaha Hadid, had an altogether different ride. Unveiled to the usual hype surrounding projects by the digital diva, the streamlined fins of this futuristic stingray were universally lauded. This would be the saving grace, the beauty queen of the park, in a motley field of cheap-looking sheds. Yet, of course, it was too good to be true. The budget escalated from £73 million to £269 million, leading the building's flaring wings to be amputated and replaced with two temporary seating stands, clumsy appendages that now overshadow the fluid form.

Moreover, this expensive wavy roof—which uses 3,000 tonnes of steel in a vast matrix of trusses—was soon shown up by the graceful velodrome, designed by Hopkins Architects, which lies a little way to the north. This concave timber shell—hovering above the track like a giant Pringle—encloses an equivalent area with a similar double-curved roof, but uses only 100 tonnes of steel in a minimal cable net structure. And it cost only £90 million. The contrast between a building designed in close collaboration with engineers from the start, next to one conjured from the parametric bowels of a computer programme and handed over to be built, could barely be more stark.

Until this week, that is.

As if providing a final surreal chapter to the story of Olympic construction, Friday saw the topping out of quite possibly the most bizarre monument to the Games ever conceived—and a project that shows quite how dangerous uncontrolled digital modeling, and its accompanying "we did it because we can" philosophy of architecture, can be. It also looks set to buck the trend of a media U-turn: most critics are still firmly dead-set against it.

The ArcelorMittal Orbit, designed by artist Anish Kapoor and engineer Cecil Balmond, is an inexplicable totem pole to Lakshmi Mittal, international steel magnate and the UK's wealthiest man—who has stumped up £19.6 million of the £22.7 million cost of this giant red tangle.

The idea for an Olympic tower was dreamt up by London's Conservative mayor, Boris Johnson, back in 2008, dazzled (and clearly rather worried) by the bombast of Beijing's Olympic Games, and its host of such instantly iconic symbols as the "bird's nest" stadium and "water cube" swimming pool.

"We decided we needed something extra, something to distinguish the east London skyline," said Johnson. "Something to arouse the curiosity and wonder of Londoners and visitors." He was after a concentrated awe-magnet, a spellbinding structure to make up for the modesty of our own humble stadia. "After Beijing, Boris felt we needed something to create a buzz," says Ian Louden, Head of Brand for ArcelorMittal. "Something to capture the imagination of the TV cameras."

Following a serendipitous meeting with Mittal in the cloakrooms at Davos, he had himself a sponsor, and so Kapoor and Balmond's entry proved the most expedient—chosen over (unpublished) submissions by Anthony Gormley and Caruso St John, presumably because theirs didn't come with a free construction package.

The Orbit was unveiled to scarcely masked gasps of incredulity—but, as ever, Johnson was quick to douse criticism through that age-old British technique: descending into farce. "Some may choose to think of it as a Colossus of Stratford, some eyes may detect a giant treble clef, a helter-skelter, a supersized mutant trombone," he quipped. "Some may even see the world's biggest ever representation of a shisha pipe and call it the Hubble Bubble."

Analogies on Twitter were generally less kind.

Now built, and visible from several miles around, the Orbit's contorted tangle of loops reads like an imploded roller-coaster, a tortured scrunch of entrails, stretched and knotted into oblivion. Richard Henley, associate director at Arup, describes how the form is, in fact, "deceptively simple," beginning as an inverted cone at the base, before rising, looping and descending to touch the ground twice, to form a tripod. "This is not a 'look no hands' structure," he says. "It is quite a coherent piece of engineering." Meanwhile, architect Kathryn Findlay has been brought in to try and squeeze all of the architectural elements—from lifts to viewing platform to the clumsy spiral staircase—into the already-designed framework, clearly no mean feat. Entering under a flaring Corten steel cone, visitors will rise up in lifts to the two-storey viewing drum—which is penetrated by an "annulus" window—before walking down the 455 steps, which spiral around the central clump of tubes.

Gifted to the Olympic Park Legacy Company, which is currently looking for an operator, the Orbit will be run as a paying visitor attraction, projected to receive a million visits per year, generating an income of £10 million, £2 million profit of which will be ploughed back into the upkeep of the park. It is, in effect, a free money-making machine.

And, like all great attractions, it is already being described by its impressive anatomy of facts and figures: the steel, assembled from ArcelorMittal mills around the world and rolled in Bolton, is made into 366 star nodes, each 4m tall, which twist and writhe, connected with 35,000 bolts, up to a height of 115m—making the completed structure 22m taller than the Statue of Liberty. "If it was unravelled, it would be taller than the Eiffel tower," reads the promotional material, optimistically.

It is covered in 19,000 litres of paint in "Kapoor Ruby Red" —a conscious aping of Yves Klein's "International Klein Blue" —also known as RAL 3003, and has been assembled by only four people, working for a year, zipping up and down cranes and cherry pickers.

As the assembled pack of journalists is ushered outside the press room, with a distinct lack of awe, for the momentous lowering of the final top loop into place, what becomes suddenly so clear is how the wonky spiral of thick red tubes, 2,000 tonnes of steel wrestled into a crooked jumble, stands in such stark contrast to the elegance of the very cranes that have lifted each of the 366 pieces into place. A parody of excess next to these refined models of engineering, the Orbit is finally revealed as a mocking mirror image of the stadium's slender exoskeleton and the aquatics centre's scaffolding seating wings—the provisional, steel-framed language of London 2012 interpreted with bloated lunacy.

Strangely, the Orbit it is so wilfully grotesque that it is almost likeable. Given the lack of site access (it won't be fully complete until next spring), all assessments have been made at arm's length—little different to the scaleless perception of the original rendering. Given time, it may well garner a cultish following—and, providing 20 mile vistas across London and a thrilling view straight down into the stadium, no doubt enjoy the traditional volte-face in the press.

Oliver Wainwright is a London-based journalist and architecture critic. He is currently Buildings Editor of Building Design magazine.