I really hope animations improve from Fallout 3 / New Vegas. It better at LEAST be on par with Skyrim, I hope better. In the previous Fallouts, the walking, running, and combat was painful to watch. They'd choppily strafe right and left with amazing teleportation skills, and they turned around without actually turning around, just rotating their bodies instantly.. I really hope they fix these things or Fallout 4 will be a more painful experience.
It's another one of those things that's improved with every game, so I'm confident. We didn't get a good look at any character faces, but if the Vault Dweller's body we see at the end of the trailer is what we get in-game (which is consistent with all of Bethesda's past trailers), then it looks damn good compared to past games.
Skyrim is the peak of character animation if you ask me. How can it possibly be improved on? https://www.youtube.com/watch?v=2HCif37nVrI
At the very least it will be Skyrim quality, but hopefully they have improved them.
https://metrouk2.files.wordpress.com/2015/06/tl1qjr7.jpg?quality=80&strip=all&strip=all&w=768&h=432&crop=1
If you look at the image above you can see a couple in the crowd holding each other and a guy sitting on the floor. Both seem to be new animations so even if the quality hasn't improved, perhaps the quantity has.