The Rage Unleashed ... 28 Weeks Later
A lot of people liked 28 days later because it was bleak, almost uncompromising* and contained elements unlike other films within it's genre. I wouldn't label either movie as a zombie movie. Technically, these people suffer from a virus and they're not dead. The people who suffer from this virus, like zombies will persist on attacking if they're not hit with a kill shot, they're bent on destroying, and they consume flesh. Unlike zombies, the victims of this plague die from things zombies most likely wouldn't -- like starvation as seen. They're not dead. They don't die and reanimate. Hence, they aren't zombies. If pitted against zombies, barring the dawn of the dead remake, they'd tear 'em limb from limb, then most likely become zombies. I only painstakingly make these distinctions because I hear people compare 28 days or 28 weeks to Night of the Dead, Dawn of the dead, and the like and while certain elements are shared, the nemesis+ are radically different and the gestation of the illness, culminating to become a new harbinger of doom -- practically instantaneous. This distinction was compounded in this movie. The sequel sets out and succeeds in making its predecessor look comfy, hopeful, to the point where the predecessor might actually seem boring.
* - Some people disliked 28 days because when it landed on the shores here, it arrived manipulated. It defied a bit of logic in order to make it more palatable and widely accepted. 28 weeks later says "I don't care if you like me or not, this is who I am!" Do I like it for what it is? Yeah. I do. I also feel it's a movie you probably shouldn't expect to walk away from feeling all warm and happy. If you usually have nightmares from bleak material, this one delivers plenty and serves it at a bloody, visceral 98.1 degrees.