Not only do shekeres make some of the best tones of any of the musical shakers I know, but they also can be used to make pretty complex and interesting rhythms. The true percussion masters can really put on a stage show by throwing the shekere up in the air and catching it in a rhythmic manner. I have seen some pretty complex things done with the instrument, things that you can not do with most musical shakers.
Nonetheless, even though shaker eggs have their charm. Most people simply shake them back and forth to get a little bit of a beat, and this is fine for using in the background of songs, but you can do so much more with them. You can slide them back and forth in a slow, sinuous rhythm that is surprising in its complexity.