I haven't had the pleasure of seeing it yet. Yes I said the pleasure. I'm trying my best to wait until it hits the silver screen.
The first thing people need to realizes is that it's incredibly hard to keep up with the original Dead trilogy. That combined with well reviewed failure of Land of the Dead (saw this twice in theaters, never regretted it). Sentiments aside I'd have to say that I was not let down by Diary of the Dead, had it been done by a new director I'd have been very happy. Taking into account the finances put towards the movie it couldn't have been done any better.
As for Survival I'll just have to wait and see.
Romero is both over and underrated at the same time, meant with no disrespect. I'd be the first to jump into a bullet for the guy, he's trying his damnedest to make a living in a world that only wants zombie movies from him. He didn't want to get stuck doing the same thing the rest of his life, but he has. He's doing his best with what he's got, living the American dream. He takes us into his heart and mind and does his best to not let us down. And if you think about it, he hasn't let us down so bad we should turn our backs on him.