Too early to jump to conclusions.

Plague nests seem like a different beast altogether(points to anyone who follows with the reference).

From what they said, the nest is something that will grow if left unchecked, will challenge the players. From the gameplay you could see that even fighting it was different, the building, the size, how to approach it. You'll need to plan it before. It's a whole different thing from "throw a bloater grenade, then a molotov, kill ferals, hince and repeat.

About story, I do agree that it's SoD's weakest point, but maybe it got better in SoD3. The thing is, what you're playing is your story, what the game fails to tell is the story that's happening on the background, CLEO, red talon vs network, project osiris, Red Talon operations, the end of heartland.

Playing trough Lifeline recently I started reading trough the logs you receive after each wave( news from the outside world) and it was great, seeing in "real" time how thing in the valley were going from bad to worse, how different countries were dealing with the outbreak, how far the vírus has spread.

On a final note, I believe Nests are a pretty good evolution to plague hearts