One thing is for certain with survival mode: it's exhausting. My nerves are in tatters! I spent an hour or so collecting resources from around Sanctuary and Red Rocket, making sure I had water supplies, beds and food provisions available at both. I also levelled up again and upgraded a 10mm pistol. I then decided to go help the Minutemen and see how tricky combat is.
In general it's... more or less fair. It is of course far more dangerous, but that works both ways and a couple of well placed shots from cover can take down a raider. I managed to get upstairs to Preston and co without too much trouble, although I took the best part of half an hour over it. At that point I thought, right, I'll go back across town to a bed before I even consider jumping in the power armour and taking on Mr D, so I went downstairs and stepped outside.
"There's someone there boss!"
Ohhhh fuck. I didn't realise the raiders were already out there - I thought their arrival was triggered by getting in the power armour, but alas no. I retreated back inside and went back to suit up and grab the minigun. Now to be fair the armour does give you a good amount of protection even in survival mode, but when our big beasty friend turned up I suddenly became very aware of not having saved in nearly 40 minutes and was starting to clench.
The worst thing about the deathclaw is not that he's big or that he's fast or that he can kill you with a couple of swipes. It's that to get his attention and bring him in range you have to venture out in the open. When I finally got his attention and he sprinted towards me I opened fire, hurtling backwards towards the church doorway and made an involuntary noise not befitting a 31 year old man. Now I remember from my first playthrough that the deathclaw can't fit through the church door, as I very much used that to my advantage. This has apparently changed.

As he followed me through I almost literally followed through in a far worse sense. Somehow I managed to empty enough bullets into him to stop the charge, but even after the XP message popped up I thought he was still somehow coming towards me and kept firing just to be sure. I then went straight to bed.
That was more intense than the first time I played System Shock 2. Survival mode is
terrifying.