I have tried Dropline before for about 15 minutes and then removed it quickly....
I found it to be too "canned"
Ximian Evolution is a pro along with Exchange connector now offered for free....
I think it makes and excellent workplace desktop.....
I didn't like the way it changed the location of certain files....
If you install it be sure to do a backup first (that should be a WARNING during install)...
If you want it just for GNOME you are better off to install GNOME not DROPLINE
All in all it is great if you just want to get up and running quickly (on a fast machine that is supported by the install)