I saw 28 WEEKS LATER last night.
I give it 7 out of 10.
It suffered from:
1. Great initial premise goes nowhere.
2. No sympathetic characters in the film to identify with. The person introduced as the protagonist is a gutless coward who is a zombie by the second act.
3. Plot didn't really have a satisfying climax.
4. A lot of gore and little humor, like WAR OF THE WORLDS.
5. Characters all do unbelievably stupid stuff.
You can make an apocalyptic movie grim as hell, (and it was) but you've got to have three elements in that movie : a likeable main character we can identify with who doesn't do stupid things for no reason, much humor to alleviate the ugliness of the situation and a good climax that resolves some of the basic dramatic conflicts set up in the film.
I wouldn't say it was a bad film, more like a close but no cigar. If you asked me halfway through I would have told you it was shaping up to be the greatest apocalyptic movie of all time ... but there is no payoff in the second half of the flick. I mean, none at all.
There are some pretty fantastic CGI effects of Britain getting firebombed by aerial strikes. I don't know if they were generated by computer or they just took these shots in France after 8 pm at night.