"The Iron Lady" suffers from a number of factors, mostly pertaining to a messy plot structure. The life of Margaret Thatcher is indeed interesting subject matter, but condensing it all into a frame narrative conversing with her late husband doesn't really work. The moments that do focus on Thatcher's real life tend to work well, even though they seem a bit few and far between. Meryl Streep is obviously the big draw here, with a believable performance as both an unconventional political leader and an elderly woman, but there are plenty of others who do a great job, in particular Alexandra Roach as the younger, dizzy Thatcher (a role that seems to have been quite looked over by many). Bad plot structure or not, though, "The Iron Lady" is definitely worth a look into.
Review of The Iron Lady
