Let me start by saying that I really enjoyed this movie, but not quite enough to give it three-and-a-half stars. The additional half-star is because, as you'll notice if you read any of my Satoshi Kon reviews, I continue to praise his films for their thoughtful and mature approach to animation. In other words, an extra half-star for having what I think is the right idea about animation's potential as a serious and adult-oriented medium.
As for the movie: This is a very absorbing story about a retired actress who, over the course of a videotaped interview, reveals to her interviewers a myriad of secrets about her life and how it went hand-in-hand with her acting career. It would not do the film justice to say that she goes through a series of flashbacks, because it is often difficult to distinguish when she is experiencing a memory from her personal life and when she is recalling a segment of one of the movies she starred in. Additionally, the two men interviewing her "travel" with her into her memories and seem to experience and even interact with them firsthand.
If "Millennium Actress's" description worries you that it will be too similar to Satoshi Kon's other works, such as Perfect Blue or Paprika, I'd say don't worry about it. I was suspicious of this possibility when I rented it, but frankly, not only is the story completely unique, but the method in which it is told is unique, as well. Yes, there is a lot of story about an attractive, spirited young woman, and there are a lot of times when you find yourself lost between reality and imagination...but that's where the similarities end. It's one thing to say that Satoshi Kon has an obvious influence here, but another to say that he is directing several versions of the same story.
This is a simultaneously pleasant and exciting movie to watch. If I were you, the next time you find yourself relaxing on the couch with some time to spare and an imagination to satisfy, pop this one in and turn down the lights.