"What did you see in Fallout 4? That will tell you what they felt was necessary to change from Fallout 3," designer Bruce Nesmith told VideoGamer. "I know in Fallout 4 there was a lot of work done on the gun combat, because Fallout 3 is the first time they ever tried to do a shooter-style game. And, well, I think the work that was done was amazing."
Nesmith is undeniably right that Fallout 3's gunplay never felt good, but necessity was also the mother of invention here. One of the game's standout features, and a little link to its isometric turn-based predecessors, was the VATS targeting system, which slowed the game to a crawl while you targeted enemy body parts: then unleashed the bullets and had body parts exploding all over the shop.
VATS was a solution to a game where the standard realtime gunplay was, as Nesmith puts it, "not good." Fallout 4 did vastly improve on this area, though I still don't think it hit a standard where I'd ever call Fallout 4 a decent shooter. A vault dweller following a dog through the wasteland
"[Fallout 3 combat] didn't hold up to shooters at the time," continues Nesmith. "Also, it's an RPG shooter, it's not a run-and-gun shooter. But a lot of work was done on that for Fallout 4. So I anticipate seeing a lot of that work go into it, assuming they're doing the same thing.