What can I say about Meryl Streep that hasn't already been said? Her ability to immerse herself in another persona is uncanny. Just as Streep transformed herself into Julia Child, so she channels Margaret Thatcher - at least in looks and sound. If that sounds like a quibble, it is.
I'm as able to willingly suspend my disbelief as anyone. And Streep is the master of facilitating illusion. She looks so much like Thatcher, she sounds so much like Thatcher, it's easy to spend considerable portions of viewing time forgetting that it's Meryl Streep that we're watching. But why must I believe that, at the end of her life, Margaret Thatcher was haunted by hallucinations of her dead husband? And if I must, why should that haunting take up so much of the film?
I understand the way that screenplays work, that telling a story in a purely linear fashion can be boring, that starting at the end and telling the back story through flashbacks is a common, acceptable device. But this screenplay requires a lengthy setup for every flashback with the senescent, hallucinating Thatcher on screen about as often as the Iron Lady. Frankly, the story of a lonely, disheveled old woman pining for her departed life companion is all too common. And I don't care how well-researched and how authentic that story might be. The story of a middle-class grocer's daughter who rises to become the first woman to lead the government of a major power without having inherited the position through Divine Right is compelling and is the story that I came to the theater to see.
In other words, like Julie & Julia, The Iron Lady spends too much time off-topic, or at least off the topic that interests me. Julie What's-Her-Name was a self-absorbed dweeb who doesn't deserve the slightest mention in the story of the life of Julia Child. Except as a footnote, what relevance does the story of a sad and lonely old woman have to the story of England's Iron Lady?