Many quests have multiple possible outcomes and there are 4 different endings for the main quest. To get the full flavour of the game you have to play through on each gender at least once. But most importantly, it's the journey that is the real appeal of this game, not the destination. I've wasted hours upon hours in the settlement building mini-game alone, but as a New Vegas npc once said, "Time you enjoy wasting isn't wasted time."