I'll begin my Fallout 4 experience in December, I'm on my 1st playthrough of DUST in New Vegas atm and loving the difficulty. I hope Fallout 4 will be a big challenge to survive early on in Survival difficulty, so is it comparable?

Fairly challenging though not nearly as difficult as the Souls series/earlier CODs on Veteran.

Combat is slower due to the fact that it takes forever for health to regen. Buff addiction is a way of life. Those Cram and other "old" foods are good for topping off your health prior to a fight. Cook everything that you can and Stimpack prior to any big fight.

I die alot.

Does ammo have weight on survival? I've been dragged away from my Xbox so I can't check.

No it's not true 'survival' mode... Personally I think calling it Survival was quite misleading.....

They should have called it 'very Hard'

However, I personally find the game too easy even on Survival...... There's such an abundance of resources Stimpaks, ammo, food.... Only careless play results in death really ...