It took about 2 1/2 or so hours. There were 3 beginners and me. Everyone loved it and had a great time. If there were 3 experienced players it would have taken maybe an hour or 1 1/2 hours.
OMG. Our games take at least 4 hours and we are 4 experienced players. What really takes a lot of time is the planning phase, where we leave the table groupwise and discuss the next turn, which adds a lot of tactical flavour to the game...