The last time our group used Roll20, it proved to be a fairly major obstacle to actually getting anything done. Part of the problem for us was actually me... the GM. I found it quite challenging trying to balance all of the new elements to the game including a number of the players carrying on private conversations with me through the main chat window while I was GMing (something at first, I encouraged).
We are playing Mouse Guard, so I imagine that it is quite doable, but as people have said before… you need to limit the use of the program to that which actually adds to your game.
I suppose you will discover how we fair for yourself just as soon as my group comes up with a name for itself