This production has its biggest deficiency in missing directing.
It seems that the director here could not contribute much, except a vision of the underground environment. Leading the actors or improving the script wasn't on his agenda, I assume.
The plot isnn't really elaborated, the script not very mature, the main actors don't show that much involvement, and production values are not the best.
The whole movie is bit of a mess, but surprisingly, it wasn't that bad,
Though most things here are cliché, beginning with the charcters, to the relations and most of the dialogs, which sometimes seem to be taken from a Lego construction kit for post-apocalyptic movies, there are some little enhancements, which save the movie from total failing.
One enhancement is of course Stanley Tucci's part, who has the easiest work, as the script serves him and him only, where it works against Smith and Dormer for most of their lines - and they both aren't charismatic enough to compensate.
But many reviews here criticize the accents, and that is the one point I wouldn't ever do, since it hastn't any real impact on a movie's quality.
The premise itself is flawed, as the virus doesn't kill or zombify people, but makes them violent - but not against already infected ones, as it seems (it is said that they roam the surface in packs). So it is a mild Apocalypse, after which we all may live together again but with much roaring and grumbling. Doesn't sound that gruesome for me.