Nothing (read NOTHING) is held back...

Rating: 9/10 (11 May 2007)

...Not this time.
I believe 28 Weeks Later did appreciate as a sequel (with only a couple very minor depreciative concepts), and that was a surprise.
I'm admittedly a zombie film fan (especially the serious, non A-Team variety). And although the Rage virus in these two films does not produce an 'undead' zombie, the 'infected' nevertheless present a similarly formidable and threatening antagonist. If you haven't seen either film, Boyle's 'infected' are far less like the traditional lumbering Romero zombies, and closer to the Zack Snyder zombies of 2004's Dawn of the Dead. Note that if you were able to get away with seeing 28 Days Later as a date movie, you may not pull it off with 28 Weeks. There is very little breathing room, and some of it is more disturbing and far less bridled than you might be expecting, especially if you are used to the character-based 'safety' of most films.
Unlike 28 Days, a flashpan start to 28 Weeks Later sets the tone for the entire film... Which although short in running time (at just over 1:30) with quite a fast pace, still seemed very much long enough to be perfectly enjoyable, especially for any fan of the genre. Other than a brief, but informative back-story conversation near the beginning, there is almost no down time spent (wasted?) on emerging relationships or overly granular side-stories. Overall the most powerful element of the film isn't really character based, but rather the theme of a terrible pandemic that, besides a small twist, isn't much changed from the first movie.
There is one facet of the film that I did not really appreciate, but can't really detail without a spoiler warning. Let's just say that London is a fairly large playground for certain (coincidental?) events to happen (and not just once). However, there's a possibility I may be missing some concept that made these events intentional--I hope it's some twist of the virus and isn't just star power.
I'll be purchasing the DVD, but probably won't offer to watch it with any of my family and couldn't recommend it as a party movie :)
Post Script: If you had ever wondered why the rest of the world was not affected by this virus, consider the geographically isolating nature of the British Isles and the extremely short incubation period of this virus. A truly viable pandemic must have a longer incubation period and optimally be airborne or at least infect multiple disparate species. So the Rage virus, while perfectly suited in close quarters would likely not travel much farther than a pair of human legs could travel.