Just took my first shot at Far Harbour and the new Survival mode, wound up playing for about 7 hours straight.
The new Survival mode is good, few kinks I'm not fond of but generally liking it. Eating and drinking is way too frequent for my tastes, really like what they've done with the need to sleep, the rest is basically fine. Limited/no fast travel is forcing me to walk more, which means I'm seeing more stuff, soaking in the atmosphere and generally enjoying myself despite the long trudging walks. Ammo having weight is annoying, if only because i favour some heavy guns with heavy ammo to match, but power armour is providing. Simply adore the higher lethality for me and NPCs, being able to kill super mutants in just a few seconds with a gatling laser is great, and my power armour keeps me pretty tanky. Makes me feel more like a badass and makes the challenging enemies feel more challenging rather than grindy.
Far Harbour I've not seen much of yet. Only gone a little way into the main quest, mostly done some side missions and mucked about with the harpoon gun, which I love. I love the atmosphere and design of the DLC, the fog, the trees and general dark and mysterious feel to the place. The new enemies are interesting enough to fight, if nothing special. I do like the variety of aquatic themed enemies though. I've felt that the new mirelurks were among the best redesigns of FO4 and I'm glad to see more enemies with a similar aesthetic. New favorite quest is part of the DLC, it's just way too fun, I was smiling all the way through it and left wishing for more missions like it. It's a lot like the Silver Shroud questline, but sadly far shorter. Not going to say anymore about it because I think people who aren't familiar with it should find it for themselves.
I've yet to find any of Far Harbour's power armour things yet, which is annoying me a bit. My suit needs new bling.