I was a little concerned about how Fallout 4 would turn out. Fallout New Vegas is one of my favorite games, but it is developed by Obsidian, while 3 and 4 were developed by Bethesda. 3 was just clunkier in comparison to NV- the dialogue was fairly bad, they had a very limited cast of voice actors, and the story was very simplistic. New Vegas had a very interesting story, with great dialogue, and a wide variety of characters and voice actors. Thankfully, Bethesda turned it up a notch (though I will say NV is still written better).
Compared to the last gen games, a decent amount has changed. It's not anything that flies in your face like crazy, but the refined combat and more polished gameplay are definite, noticeable improvements. The gunplay has more of a Bioshock vibe—it doesn't play like Call of Duty, but you're also not standing still by an enemy shooting at them, which is what would tend to happen in 3 and NV.
The inclusion of a settlement system adds a whole new layer to the game. It gives meaning to all the random junk lying around in buildings, and is a fun little side task, while also being a huge time sink if you really get into it. The only real issue with it is that they never really explain how to do a lot of basic workshop functions. Thankfully, plenty of people have written guides which are easily found with a quick Google search.
The only things I disliked in this game are:
-the dialouge system is simplified. You only ever get 4 dialouge options, and dialogue just isn't as interesting as in NV. However, their implementation of the dialogue wheel is better than how Bioware did Dragon Age 2. At least the summaries match up more with the actual dialogue.
-the stat and perk systems have been merged and simplified. It locks a lot of skills behind level caps that had not been previously tied to level in past games. It's definitely easier for newcomers though, so I can somewhat understand.
-the writing could be better. Overall it's better than 3, but still a step down from New Vegas. I am glad that they took note of NVs multiple factions, rather than just having a good and an evil faction like in 3.