The '28 Days Later Aren't Zombies' is a far too nerdy argument for my taste, and it's old now too... I mean I totally get it, but it doesn't serve the genre to try and sub-categorize or dissect it IMHO.
It hits it all: world has fallen apart , man is prey, one bite you're screwed, they're not affected by pain. It's a good, creepy movie. Why cast it off because they run fast and they aren't precisely 'risen from the dead'?
Like I said, I like slow classic zombies, but I'm nothing if not adaptable