Trying to determine where monster movies fit in terms of genres is rather tricky. All of them have touches of science fiction, horror, and fantasy, which only results in difficultly when making best of genre type lists, although that doesn't matter in terms of quality. The best monster movies are well crafted, often intelligent, and very enjoyable: films such as Godzilla (1954), King Kong (1933), The Host (2006) and Cloverfield (2007). Monsters (2010) is rather aptly named, and should rightfully be added to that list as it is indeed well crafted, with smart direction and is tightly paced despite containing enough layers and depth that it could have been maybe even three hours long instead of its 96 minute run time. However the rule of leaving your audience wanting more is wisely observed, and the base simplicity of the film which everything else is centered around results in a great, engaging movie.
Clearly made on a lower budget than most monster movies (the camera style is pure found footage type realism, which only gives the movie an added human touch and edge) and the score is quite minimalistic, which I rather liked as it enhanced the movie instead of distracting from what was happening onscreen. Furthermore, the movie features only two main characters, Andrew and Samantha, who are forced to journey through the so called "Infected Zone" in order to reach not only safety, but to get Sam home. Due to the creatures existing there, what was supposed to be a quick trip turns into a dangerous odyssey that also results in some truly gorgeous cinematography. Considering that the film picks and chooses when to showcase the alien creatures, Monsters has a romantic subplot filled with drama that makes the viewer wonder if this isn't a love story with monsters on the side. Even as the political implications of the movie are only thinly examined and looked at, this tender romance forms the film's strong heart, and results in Monsters being something more than just a creature feature with two people randomly walking through Mexico.
Not to mention the fact that the movie at times felt as if it was borrowing from equally stronger or better movies, as there are two scenes in the film that feel very influenced by Jurassic Park (1993), which I don't really mind-if you are going to steal or borrow, take from the very best. Those scenes also happen to be rather creepy and tense, so if you are looking for the horror elements of the film you would find them in those quiet, unnatural moments. There are plenty of haunting images, and of course the movie presents a type of running commentary on the problems of immigration (something that the filmmakers deny as being intentional according to IMDB.com's trivia section) which in the end really is not properly covered, something that is not entirely a bad thing since it would have sacrificed too much of the fascinating relationship between two different people. Any good monster movie actually focuses on the people that are affected by these strange events in time, as they are people often brought together by forces they usually do not understand. Life works in that same odd sort of way, and we never know why. 95