At least as interesting as the movie itself is the story behind the movie. Instead of using make-up or different actors to make the Brad Pitt and Cate Blanchett look older, they used CGI (!). And it looks astonishing. In this video from ted.com a digital expert from the company that made the Oscar-winning technology explains how they managed to do it.
It's very interesting how they handled the nearly impossible job. Furthermore, it proves that the craziest things can be possible if you just think further than the usual boundaries. Of course Benjamin Button is made with an almost unlimited budget. But if you think money limits the use of special effects, take a look at the genius solutions in the Gondry-movie Be Kind Rewind. When there's an idea, there's a way.