The moment an actor signs on to impersonate a well-known figure in a film is the moment that actor gives up any chance of delivering a naturalistic performance. Impersonating a famous person requires too many affectations of voice and manner, and too much high style, which overwhelm the everyman quality that neorealistic acting demands. If tremendous affectation doesn’t bother you, then you’ll likely find nothing to criticize in Meryl Streep’s performance in Julie & Julia, another Nora Ephron meringue of a movie that, this time, features literal meringue here and there, as if Ephron finally got snagged in her own worst metaphor. Perhaps it was only a matter of time before Streep took on Julia Child, because it’s hard to imagine anyone else cast as the pituitary dynamo who fills a movie screen as completely as she once filled a television screen. And if you enjoy Ephron’s body of work, which includes Sleepless in Seattle and You’ve Got Mail, chances are you’ll fundamentally disagree with this review’s star rating; but I’m not sure Ephron can hide behind genre when she casts powerhouses like Streep and Stanley Tucci in leading roles, and when she depicts cultural icons like Julia Child. That kind of movie deserves genuine inspection.