Finished. Bad news first: characterization and plot in "Idoru" are aspects that border on anorexia. Gibson favours mood over action, and characters don't do much other than going from point A to point B and then back again. The few conflicts of interest between characters never reach a threatening magnitude and the residual climax is easily and quickly dispatched.
Where this book fails in narrative, it compensates with poetic post-modern bursts of Gibson's futurist and otherworldly Tokyo, the design and technological artefacts dominating most chapters. Brands with exotic names, daily life conducted under the aid of Tomorrow's products, the idiosyncrasies of Japanese culture. I would call "Idoru" a travel guide for a fictional city with additional footnotes on product design.
Milder than its precedent "Virtual Light" of the Sprawl saga, or the later "Pattern Recognition", but still cool.