Last October, when a journalist at a news conference in Spain asked Frank Gehry whether his buildings were more about spectacle than function, the jet-lagged architect angrily responded by gesturing with his middle finger.

Righteous snub or insolent posturing? That depends on whether you consider Gehry, now 86 years old, to be one of our greatest living artists or a purveyor of self-indulgent sculptural excess.