I upgraded from v4.06 to v5.00. I have only used it once since then, not sure if I like it or not, they changed a few small things that I noticed.
I have mine set up to show depart to destination line on the map screen the changed the goto line a little. They also changed the order of the database screen, when you have a map loaded it is now at the top of that screen, not sure if I like that or not yet. There was a list of things changed posted in the yahoo Meridian group here just have to do a search.