The story line involving alien beings left alot to be desired. The temple in South America was the most realistic historical part of the movie. With the other Indy movies, there was just enough mysterious historical links to bring some believeability to the story...thats a big reason the first movies held us captive, and we wanted to watch them over and over. The blieveability factor is important even if we know it is a ficticious story. The Kingdom of the CrystalSkull "burried" that believebility as the Alien focus became apparent. Loosing the link to possible realism lost the the Indy fan in this movie.