I don't know why they compare The Host to Jaws and Jurassic Park on the DVD box. It really has nothing in common with those films. I liked Jaws, wasn't so keen on Jurassic Park, but I thought The Host was great. I can't think of any film that I would compare it to. It's just not like anything else.
The Host is quite a strange little film. We are shown the beast in all it's full glory at the earliest possible opportunity. This is not a criticism however, as it works. It means that the story can skip the part where they try to convince the dumb officials of the monsters existence. The monsters existence is never in question. The monster also acts quite strangely. Sometimes it spits people out again, sometimes it swallows them for good or sometimes it carries them around with it's tail. Why it does what it does is not important. It's a mutation, it's supposed to be weird.
The Host is not all about the monster. In fact you could argue that the main subject of the film is really an abduction and the way the relatives come to terms with the loss of their youngest family member. There are plenty of sad moments, especially one where they all pretend for a minute that the missing daughter is back with them and all give her some of their food. The family also argue a lot and have various issues with each other, but manage to put all that aside and focus on hunting down the monster and getting back the daughter.
It's hard to call this a serious film though as it is littered with little comedy moments and lines. For instance, when an official (who is dressed in a full chemical warfare outfit) walks in to talk to the bereaved survivors, he slips over for no apparent reason other than to stand up again and pretend that it didn't happen.
Or, there is an bit where the Grandfather is making an emotional speech to the family as they prepare to hunt the monster, but then the camera cuts to the brother and sister who have both fallen asleep.
All in all The Host is exciting and sad but also can be quite funny. Well worth a watch. You might love it!