It's worked very well for us. We do use voice chat, but tend to be in character in typed chat and use the voice chat for OOC things.
Intially this kind of thing is all about patience, as Steel Wind mentions. It doesn't take long to get to a point where you don't think about the interface and just play, and that's where you want to be.
I recommend working out some technical things in advance of the first game. If you're using voice make sure that everyone can connect and communicate. Have each player connect to a test session of Fantasy Grounds on your server. Essentially, even if it means setting up a session where you do nothing but these things, I think it's better to treat connectivity and technical issues seperately, rather than as you try and work through that first RP session.