Art and sound design is as ever pretty fantastic - it's the one thing bethesda does very well. Ignoring oversights and desperate attempts to keep hold of the generic look (setting up a new fence out of wood, already half fallen down?) the ambient noises, enemy sounds, weapon effects, power armour sounds in particular, all fantastic, and the design front is fantastic. As a propmaker type, i like beth's fallouts purely for getting hold of the artbook and references.
Also a surprising amount of thought put into a lot of the designs (Absolutely none in others, but i suppose it depends on who was actually involved in making that part/section.), like the new protectron profession-types, revamped more military sentry bots, car types are a lot better designed/more 'real' than fallout 3 in some way i can't quite put my finger on?, obviously the tweaks to the power armours i love (Sacrilege as it is, making the T-51 or APA look more realistic and actually wearable without screwing up the general design is not easy.), big fan of the variation on weapon customisation, though i don't think it should be as easy as it is.
Noticed earlier that unlike fallout 3's weird, sort of junker-planes halfway between B52's and spitfires with jet engines tacked on, the crashed jets in this one seem to be based on Horten 229's? Very similar in any case, to the point where i really doubt it wasn't referenced. Which makes perfect sense.
Dungeons are done well, they're quite good at those, shame there's not a single compelling quest reason to go to them and it's purely to sate the XP grind.
Do enjoy the little comments from people as you wander - much better job of that this time, genuinely funny comments from some of the diamond city guards as you pass in power armour, things like that. Though i imagine it would grate on you after a while, in a similar vein to skyrim's "Favour the bow, eh?" and obsession with snack food comments. Still, walking through a town of people is quite well done, as long as you don't in any way attempt to speak to any of them or interact in any meaningful sense.
Basically so long as you're just picking a random direction and wandering, it feels 'right'. As soon as you try to actually do a quest or get into any of the story, it all just falls apart a bit.
Oh, and brotherhood are much better this time. By no means are they the same, or even overly similar, to the west coast BoS, but i'm so happy to see they've changed them up from Fo3's lawful good protectors of justice and rightness and kittens. They're different, but they're still morally ambiguous, and now pretty overt about their somewhat genocidal xenophobic ways. Much better.
Also i guess shooting isn't complete shit now, but if i was going to play a game for its' ability to accurately simulate shooting a zombie in the face, i wouldn't be grabbing a fallout game. Somewhat missing the point. Nice addition though.