I am on my 4th replay and I'm still discovering new dialogue paths, quests and dynamics - amazing!
Case in point, the opening quest with the NCR Ranger with the Brotherhood of Steel - there are so many options in just that opening - all covered by dialogue - it is exceptional!
Or the way the Powder Gangers are spread throughout the game - hints are given early on and then followed through on later - excellent!
I truly hope Fallout 4 will feature such depth. Obsidian should be proud!
J