I started a game on Survival difficulty. The DC in Concord was actually easy to defeat, just sat inside a building (he can't fit through the doorways) and sniped him with the minigun in Vats until dead.
Far harder is the fact that for the first part of the game you're basically forced to sneak around and avoid certain enemies and not proceed with certain quests that confront those enemies. For instance, I ran into two groups...Gunners and Super Mutants...where I basically had to load an earlier save and go around. As I understand it, LATER you'll have enough life and weaponry that you can take them.
The hardest part for me is that it seems like random loot is EXTREMELY nerfed on Survival. I'm sure I'll get a lot of "random is random," but I have four fusion cores that I've found or bought from Vendors in the same time frame that I had 21 on my Normal character, not to mention a huge shortage of uncommon and rare crafting mats, ammunition and caps. That and the dramatically increased life that enemies have.
You'll also notice on Survival that where YOU are punished with extremely slow heal rates (stimpacks are just as slow as food for some reason) enemies are NOT punished, and if a raider stims they will heal at the same fast rate as normal. Legendaries of course still heal to full after mutating. Since enemies have like 4 times the life as before, this can be excruciating.
There also seems to be an issue with the "Legendary" appearance generator, since increased difficulty is supposed to increase the number of legendaries that appear, and so far there doesn't seem to be any difference between Normal and Survivalist difficulty.