(Part of my series on watching every movie in the IMDB's top 250)
All About Eve is easily the cleverest movie I've ever seen, dialogue-wise. Despite the fact that I was watching it with company, on more than one occasion I rewound the movie just so that I could appreciate all the nuances of particularly well-crafted line.
All About Eve is also one of the few movies where every single premise is believable. It tells the story of a freshly 40-year-old stage actress who grows anxious that she's getting too old to play 20-somethings characters like she used to, and grows increasingly paranoid that the raving (and very attractive) 20-something-year-old fan that she just hired as a valet will be the one to take her spot. It's a story that very closely mirrors the actual lives of the actors in the movie, making their portrayal so much more convincing. In a way it's like a really well written reality show-- to the point that you may forget you're watching a movie at all.
Not much action takes place in the film -- one person on the commentary remarked that the most eventful scene is Bette Davis rushing briskly down some stairs -- but it remains gripping all the way to the end, where it quickly morphs from a drama into a mystery of sorts. Marylin Monroe has a scene or two, where she is well cast. But more importantly, George Sanders plays exactly the character I wish to become in life.