Reviewed - Factory Girl:I'M still not quite sure what Sienna Miller looks like. The blond underpants mannequin has such an indistinct persona that just blinking can eradicate any memory of her features and cause the cinemagoer to again wonder who he is looking at.

You might argue that Edie Sedgwick, the icy model and pseudo-actress created in Andy Warhol's Factory, had a similarly ethereal identity and, thus, that Miller might be the perfect person to play the doomed heiress. To be fair, Sienna is not bad in Factory Girl. Her football-rattle accent - an attempt to communicate Edie's patrician origins - does remind one of the worst bits of Jennifer Jason Leigh, but she holds herself with dignity throughout and has an inherent fragility that proves useful when, after Warhol loses interest and fashion moves on, Sedgwick descends into drug addiction and terminal depression.

The monotonic, deadened Andy offers such a modest challenge to actors that even David Bowie has triumphed in the role, but that is not to take away from Guy Pearce's equally admirable take on the powdered automaton.

But, my word, everything else! A key scene in Factory Girl comes when a friend of Edie's suggests she might like to meet a Very Important Person. In walks Hayden Christensen with tight curly hair, a voice like sand and glue and - you're still not there yet? - a harmonica strapped around his neck. We understand that Bob Dylan wisely refused to allow the film-makers to use his name here, but the subtlety with which his alter-ego is introduced suggests the sort of costume drama that might first show us George Washington standing guiltily beside a felled apple tree.

There is worse to come. Though the personal drama is effective enough, Factory Girl's depiction of the artistic underworld of 1960s Manhattan is carried out at the level of a French and Saunders parody. Nothing is more unintentionally hilarious than the sight of five rigid, serious-minded youngsters strumming along to an anonymous drone that doesn't really sound much like The Velvet Underground. Like all the other briefly glimpsed versions of pop icons, these Velveteen Undertakers seem to have been made as blank as possible, so as not to interfere with our own memories of the original artists.

Here, yet again, we have the 1960s presented as a theme park. Enter if you can be bothered.