Page transitions is a free utility
Page transitions are available since version 4 of Acrobat.
Beginning with version 6, they are all available in the Pages navigation panel.
In Acrobat they are available as a drop down menu : not very user-friendly since you cannot easily figure the final behaviour.
So, they must be tested one by one and this is very time consuming.
Thanks abracadabraPDF for finally providing an easy way to preview page transitions!