For a crummy made-for-TV film, this movie's got a lot of biggish name: Casper Van Dien, the dad from Ugly Betty, Toad/Darth Maul, and Danny Trejo. And they do a pretty good job, given that they've been micromanaged to hell.
The story is basically Heart of Darkness except with vampires and set in South America. There's even a scene with a French plantation owner, which I can only assume is an homage to a deleted scene from Apocalypse Now. Am I giving the filmmaker too much credit? Maybe. Casper Van Dien has to take his platoon up a river to find his ex-wife who's unknowingly stumbled into vampire territory. Thankfully there's very little philosophizing about vampires and most of the movie is dedicated to hunting and killing vampires. And saving the rainforest.
I don't know why but, for some reason, the filmmaker decided he really needed to make a point about environmental protection. Instead of using subtext an metaphor to deliver his message, the writer/director/editor/composer simply wrote in a speech about how America is destroying the earth. However, the lines are given to the villain which has the unfortunate effect of negating his well-made point.
There's something weird about moderat budget direct-to-video that I have a hard time pinning down. I think it's the sound. Good sound his hard to do. If you've got money for CGI and wirework, you have no excuse for a crappy sound mix. But the sound in Slayer is very strange. It's like the room tone was stripped from the audio track and replaced with...nothing. The film lacks a certain depth, not story depth (although there is little of that), just a fullness that you experience in slightly better films.
That's not to say that Slayer isn't competently made. Kevin VanHook gets a lot of work, so he knows how to make a movie. If you like Saturday afternoon Sci Fi Channel fare, or happen to be a Danny Trejo completest, this film's for you. Except worse.