I'm about 7 hours in now and enjoying it a lot more than earlier impressions. It's a weird title. I kinda feel that Fallout 4 represents Bethesda just saying "fuck it" to RPG holdovers from the 90s style of design and leaning far heavier towards a more action-RPG built within the framework of the open world games they're renowned for. They've stripped back a lot of the narrative depth, intricate stat play, and other stuff in favour of action driven game systems that still have a lot of customisation and variety but are less about dice rolls and stat checks and more about real time interactivity and customisation. It's a lot like how the Mass Effect games are designed.
For these reasons I'm enjoying it, because it seems more comfortable in its own skin, if that makes sense. Often it just plays like an open world shooter, and decently well enough as one. Great sound effects, gunplay is hugely improved over Fallout 3 and New Vegas. Exploring still feels pretty good.
I dont think this stuff is a case of better/worse, but just explicitly different. When I compare Fallout 3 and New Vegas I see two games built on near identical framework, only one a far, far better RPG. Fallout 4 goes for its own thing, in many ways the kind of game Bethesda has been working towards given the changes and accessibility introduced in each game starting with Oblivion.
That being said I do think the game has some failings judged by its own merits, particularly the writing and acting. No real way to dance around it; I fucking hate everything. Or not even hate. It's boring. The quests are boring, the characters are boring, the dialogue is boring, the dialogue trees barely exist, I don't want to talk to anyone, I don't feel any authenticity or weight in emotions behind anything anybody says, etc etc. It's impossible for me to give the slightest fuck about anything going on because the characters, narrative, and dialogue are so flat and dull. Bethesda really fucking stinks in this department, transforming their games for me into more of a big sandbox to fuck around in and see shit. Which is fine because so far that stuff is good, but narrative/characters/dialogue still play a big part in the overall package and it's a shame Bethesda just keep fucking it up.
Oh also, and I'm probability in a minority here; despite being fun games to just explore and wander, aesthetically and stylistically I find Bethesda's famed open worlds to be massively overrated. Fallout 4 to me has no natural believability to most of the landmass. The density of locations means there's no real negative space. There's no coherent flow between set pieces and points of interest. It's like a hundred different points of interest that range from forgettable to interesting made by different people and then all slapped together in a grid. Bringing it up is beating a tired horse, but Wild Hunt really spoiled me in this regard.