While lovers of all things zombie can find things to like in this movie, it's ultimately a pretty poor effort.
The acting is variable (one guy makes Keanu Reeves look like John Gielgud), the script is flawed and it is difficult to judge as a film as it just comes across as a student film project. So rather than shuddering with fear at the mouldering undead, you find yourelf thinking, "Yowch, that guy is a bad actor. Couldn't they find someone else?" or "Considering they've got a £100 budget these zombies look pretty good!". And that is what is so sad about this film. The film-makers cope admirably with the problems of a low budget; the make-up is great, there are some nice shots of empty streets and so on, and there's even a military incursion (by a real Army platoon!). But where it comes apart is the bit that is unhindered by budget - the script, which is deeply flawed. Of the three stories, the second is ultimately pointless and in none of the stories do you care about (or even get to know) the characters. It also has absolutely nothing new to say about zombies - there is no new take on them, no new perspective. It's taken as read that these are shuffling Romero zombies who are dead and can only be stopped with head shots despite the fact that the zombie plague is caused by some kind of flu virus a la 28 Days Later. And while the SFX are great, the budgetary restrictions do mean you rarely see more than three or four at a time, and "shufflers" aren't exactly scary unless there is a horde of them or as another reviewer said, you are trapped with them in a confined space (and sadly 90% of this film takes place in woodland and fields).
Worth watching if you like zombie movies, but really this is something that if an amateur film-maker friend of yours showed you, you'd be impressed by, but judged by "professional" standards is distinctly below par. (That said, it is stil better than the later Romero steadicam-zombie film, "Diary of The Dead", although that is rather damning with faint praise rather than saying anything good about this particular film).