The stage is bare except for a solitary mic stand. When the curtains part, they reveal Smashing Pumpkins’ singer and guitarist Billy Corgan, dressed sombrely, except for some flapping silver fabric that looks like half a skirt. An acoustic guitar slung around his shoulders, backlit, Corgan basks for some moments in the cheers of the near-capacity arena. Then he kicks off the penultimate date of this much-vaunted Smashing Pumpkins reunion tour with – of all things – a solo acoustic track.

The scene-setter is Disarm, first released on Siamese Dream, the Pumpkins’ 1993 album. It is perhaps the singer-songwriter’s most poignant few minutes, in which he addresses the abuse he suffered as a child. Infamously, the 90s alt-rock titan didn’t write a vengeful grunge kiss-off, but a furred, blithe ache of a tune, that sought to “disarm” his childhood tormentors “with a smile”. Throughout, Super-8 films and childhood pictures flash up, scribbled over, his eyes x-ed out; as the song ends, Corgan, 51, turns to the backdrop and salutes his younger self.

It is, on one level, hugely moving. Anyone who has made it out of an unhappy youth deserves to pay tribute to their powerless larval phase, to hug the kid they were and tell them that it is all going to turn out OK, give or take a few dodgy pro-wrestling ventures (Corgan runs one). There is, however, something a little telling about starting one of the most-vaunted reunion tours of recent years with a song that makes a point of excising the rest of your band from the get-go.

The Pumpkins were very much a band that had their cake and ate it, garnering critical acclaim and selling piles of records hand-over-fist during the last hurrah of the albums industry. They will forever be associated with the 90s, but their sound has aged remarkably well.

The band finally arrive for Rocket, an early triumph from Siamese Dream, its circular guitar riff searingly loud. Soon, we’re into Siva, the loftiest peak of the Pumpkins’ immense debut album, Gish (1991), ebbing and squalling.

Watch Smashing Pumpkins’ video for Disarm.

You cannot fault this three-hour set for its three-guitar assault, which sometimes verges, enthrallingly, on scientific experiment as roiling, distorted guitars make like low-flying aircraft and shake the plastic seats on songs such as Drown and Porcelina of the Vast Oceans, whose sprawling length apes the live excesses of the Cure.

You could, though, just come for the first third and the final third, leaving out the portentous cover of David Bowie’s Space Oddity that Corgan sings from atop a metal staircase wheeled on for the purpose, and, indeed, the whole middle hour, in which the early promise of Gish and Siamese Dream gives way to a series of more long-winded iterations of Corgan’s once appealing melodic and thematic signatures.

The absence of Wretszky is either not addressed or, perhaps, dealt with indirectly

The singer, who despite being on an extensive tour welcomed a baby daughter earlier this month, changes costume frequently, rocking looks that range from little-Nosferatu-lost to cybergoth monk to silver-hatted Elton John-alike at the piano to medievally robed mage. For the encore, he’s a ringmaster and sports a fez with a handle on top. The visuals obsess over showgirls and Catholic imagery, Italian futurism, zoetropes and magick.

At some point, Danish singer Amalie Bruun sings a cover of Fleetwood Mac’s Landslide. Its sole purpose, it seems, is to delay the rest of the good Pumpkins tunes: a superb Cherub Rock, and the instances after Siamese Dream when Corgan managed to bottle lightning again – Ava Adore from 1998, and Bullet With Butterfly Wings, from 1995’s career-peak double album, Mellon Collie and the Infinite Sadness. “Despite all my rage, I am still just a rat in a cage,” snarls Corgan, uncharacteristically nailing a feeling that every malcontent acquainted with amplification can relate to. His other lyrics mostly tend to the solipsistic and oblique.

Corgan may subcontract a number of guitar solos of the reunion tonight, but no one who has ever dallied with the Pumpkins over the past 30 years has ever been in any doubt that it is, categorically, the William Patrick Corgan show. This Shiny and Oh So Bright tour was meant to mark a break from the largely solo iteration of the Pumpkins that has been operational for more than a decade, with the band’s imperial 90s line-up burying hatchets, unspooling the hits and recording new songs as a group.

Billy Corgan at Wembley Arena. Photograph: Roger Goodgroves/Rex/ Shutterstock

The first part of a two-part album – Shiny and Oh So Bright – produced by Rick Rubin, is coming on 16 November, subtitled Volume 1: No Past. No Future. No Sun. We get a pretty decent song from it in the encore.

But the album, and the tour, are operating at 75% authenticity. Corgan, original guitarist James Iha (in a dapper white suit) and founding drummer Jimmy Chamberlin are joined by supplementary axeman Jeff Shroeder, on board since 2007, and keyboard player Katie Cole. Shroeder, not Corgan, plays Jimmy Page on the Pumpkins’ quite unnecessary rendition of Stairway to Heaven.

On bass is Jack Bates (son of Peter Hook), whose white trainers and polo shirt lean more towards Oasis tribute band than the stylised rococo medieval Pinterest mood board Corgan has been refreshing for some years. Bates stands in for original bassist, D’arcy Wretzky, who left the band in 1999 battling addiction; she now works with horses. As Wretzky has told it, through a series of screen grabs of text messages between herself and Corgan and an extraordinary interview in February, the negotiations for her re-entry to the band were fraught, with money and the extent of her contribution contentious issues. (The band line goes thus: “Despite reports, Ms Wretzky has repeatedly been invited out to play with the group, participate in demo sessions, or at the very least, meet face-to-face, and in each and every instance she always deferred.”)

As the Pumpkins revisit half a dozen of their albums, the absence of Wretzky is either not addressed or, perhaps, dealt with indirectly. During Try Try Try, the band’s sympathetic anti-addiction song from 2000’s Machina/The Machines of God album, the backdrop features a video of a bleached blond woman shooting up with glowing drugs apparatus, then waking to fumble around with empty wine bottles.

It is all pretty dispiriting, this long-winded carnival of disingenuousness. Not even a churn through the beatifically heavy Today can derail one overarching impression: that three hours with any line-up of the Smashing Pumpkins is roughly two hours too many inside the mind of Billy Corgan. The visuals for Today feature a reimagined tarot deck; virtually every image features a figure that looks suspiciously like Corgan.