Slither is a movie that doesn't fit in most well-known categories. It's a horror film with a little sci-fi on the side. It has slapstick comedy, a bit of sick/twisted humor, and an 18 year old Mature rating, yet no real graphic sex (well, nothing human anyways). Slither even has a little drama as it depicts a forbidden love story that looks as if it was ripped out of a soap opera.
Screenwriter James Gunn (Dawn of the Dead) admits it himself in one of the bonus features on the DVD: He's trying to bring back the style of some of the 80s funny/horror combo movies. By the way, for those who like extra features on a DVD, this one has a lot. On top of the usual deleted/modified scenes, it has some funny outtakes, a hilarious feature on who is Bill Pardy, and lots more including how to make your own home brewed fake blood.
Personally, Slither reminded me such horror movie classics as The Blob, Attack of the Killer Tomatoes and Trucks. None of those movies were truly scary, even if there was plenty blood and horrific things happening to people in them. If you're hoping to feel horrified by this movie, stop reading here; it won't happen unless you are a total wuss. It only takes a few minutes into the movie to guess that the treatment of the story isn't totally serious, but once you're on board with this idea, you get the feeling that some "horribly" funny things will happen. And yes, the pun is intended.
The story follows the misadventures of the isolated southern "hick" town of Wheelsy, where they are about to hold their "Deer Cheer" festivities when a meteorite carrying some weird lifeform lands in their community just before deer hunting season. (the term "hick" here is used for lack of a more politically correct term, like "culture-challenged" for example). The town has all the stereotypes of such a community, and the names of businesses in the town even reflect the names of classic horror movie directors that James Gunn has admired through the years.
The characters present in the movie are as follows: There's Starla, a very good looking young woman teacher in the local high school who once dreamed of becoming a Hollywood star; her jealous husband, Grant Grant who is probably 15 years older than her and paid for her education in exchange for her marrying him (yeah I know, his first and last names are one and the same, only in America!!! the newly appointed police chief Bill Pardy (played by Nathan Fillion of Buffy the Vampire Slayer fame) who has had a lifelong crush on Starla; the town's colourful mayor Jack MacReady who has a hard time not swearing every 2 or 3 words; and finally one of Starla's students, Kylie Strutemyer, who inadvertently becomes involved in the story after she survives the attack of some of the movie's creatures.
The story itself is quite predictable as it inherits a lot of old classic twists, which disappointed me a bit, yet the fact that it has some twisted humor and some stuff which is "just wrong" made me laugh hard enough that I forgot about the unoriginal plot. As pure adult entertainment, the film gives you this funny horror factor that can be enjoyable as long as you understand why the story is told that way. I don't think puritan-church-going-conservative adults will find anything funny in this movie, but that's probably the reason why it was given an M rating. There's blood, sexual innuendos, foul language, space aliens, and dark humor. If you ask me, that's reason enough to watch it. Again, I must stress the fact this isn't a horror film, it's a horror-comedy-drama-suspense-sci-fi if we need to name it something. I'm still not sure what to think about it, and therefore I think it is worth seeing for the curious viewer... Maybe you can find a better category for it than I could.