Monster movies have often provided a way of talking about the concerns of the day and The Host, with it's industrial pollutuion and givernment conspiracies is no exception.
Where The Host does break with tradition is that the monster makes its appearance pretty much as soon as we're past the opening credits. But what a monster it is! If spectacular special effects are the bag that you're into, then this really is a film that you need to see.
The plot itself, however, prefers to focus on the family of one of the monster's (still living) victim and, here, it does a great job of finding a balance between comedy and tension. Although the characters are often slapstick in their behaviour, you do find yourself starting to care about them and it's this that keeps you hooked on the film.
And the ending is one of the best I've seen in a long time