I have about four hours into this game, I'm loving it.  Much more than I anticipated.  Still doing megaton missions right now, getting some things for Moira.  The sense of scale and the wasteland setting is amazing.  I try to quest during the day as well!  
I ran into one super mutant early on....but he was a friendly super mutant!  Uncle Leo, strolling the wasteland trying to bring peace and harmony.  When I first saw him at a distant, I crept up slowly.  I noticed no red icon was popping up saying he was an enemy so I went for it and we had a nice chat!