Okay, general impressions after 3.5 hours playing:
1. Seems to be relatively well-optimized and bug-free. I've been playing with all settings maxed out and haven't suffered a single drop in framerate, which has stayed very smooth. No CTDs. No floating rocks/trees or holes in the world. There's only been one thing at all buggy, but that's a bit of a spoiler on a fun little encounter.
In the scrapyard with the malfunctioning sentry bot, attacking it will push it inside the cars and rubble around it. I suspect that's a one-off thing having to do with how they got it to behave like that.
2. Dialogues are improved. People have more expressive faces and move their bodies when talking. Cutting to the third-person camera helps with the old corpse-stare as well. However, eyes are still dead-dead-dead, and the mouth-flaps occasionally bug out.
3. I was right, power armor is fueled by power cells. Thankfully neither they nor replacement armor panels seem too rare; I've found two more suits apart from the initial one and 5 extra cores just wandering around randomly.
4. JESUS FUCK DEATHCLAW SCURRY.
5. Creature combat is generally improved by the burrowing. I tried to cheese a Giant Radscorpion with a cliff, but it burrowed to the top from the valley it was in. Q.Q
6. Ghouls got the revamp they needed. They look much better, and ferals are scarier to fight.
7. Doge is a bit annoying, tends to stand in your way (as per usual). The whole "lead you to treasure" thing is a mixed bag; I've had him find stashes of good loot, but I've also had him lead me to random baseball bats and safes I've already found but can't open.
8. They definitely did better on the little things. I've found lots of funny, quirky bits and bobs that aren't in-your-face about it.
Like the laundromat in Lexington. If you look at one of the dryers, it's got a full set of human bones inside it.
9. It's kind of awkward having the scroll wheel control both first/third person switching and scrolling through loot.
10. Loot lists display armor/weapons with plus marks when they're better than what you have equipped. Neato.
11. Weapon modding is pretty deep, but requires a shitload of scavenging. Now you've got a
reason to carry around ten thousand bits of crap! Adhesives are especially valuable.
12. You can store stuff in the workshop inventories, I'm
pretty sure that they're persistent.
13. The new layering of the rad-meter over the HP bar is great. Also the UI element color being a RGB slider set instead of a couple presets.