My overall impressions of Fallout 4 (no spoilers)
Pros:
Factions are a let down from New Vegas but Bethesda did a good job giving each of them purpose and livelihood to them. There is no clear bad guy - they are all equally messed up and have good ideas behind them. That kind of moral ambiguity is something unexpected from Bethesda and I do appreciate it.
The main storyline itself is not as strong as New Vegas but a huge improvement over Fallout 3's terrible and rushed plot. I'd also say it is better than Oblivion and Skyrim's. There are a lot of hard choices to be made here and they keep you invested with tons of twists and turns.
Atmosphere is once again the strongest aspect. Locations feel real despite how hard it may be to actually believe the formation of some of these settlements. Monsters are terrifying instead of just being bullet sponges. Weather can change, from rain, to radiation storms.
Companions were well designed and have good perks to them. Huge plus from Fallout 3's pathetic companions (sans the amazing Dogmeat). It doesn't live up to New Vegas where every companion had at least an hour worth of side content with a plethora of perks and choices.
Character creation is amazing. The best in console gaming so far.
Cons:
Not enough choice. When it comes down to it, there are really only four huge choices within the game and they are all delegated to the main storyline. It's kinda shocking coming from Fallout 3 and New Vegas where you had tons of choices.
Not enough settlements and NPCs. This is something that felt really strange considering the world is supposed to be bigger than any other modern Fallout game. Where is everyone? Why are there such few towns compared to games from the last generation?
Not enough meaningful sidequests. There's one or two good sidequests in the same that are as memorable and impact as Reily's Rangers and nothing really as diverse as Stealing Independence, Head of State, Blood Ties, or Agatha's Song. It's a little disappointing.
I'll be starting another playthrough soon to see the other ending. Excited for the upcoming DLC.