The differences between the V2 and V3 are essentially cosmetic. A few of them are:
-Bigger, better layed out screen and more user friendly navigation.
-Displaying up to 6 logging channels at once.
-A much more modern look with user customizable face plates
Whether it's worth it or not is up to you. It's like asking yourself if you really need the latest and greatest Iphone/Android or if the one you have will do.