"Serum" starts out with credits that are quite reminiscent of the "Re-animator" movies, and it owes a lot to them. The story is very similar; a mad doctor develops a serum that he believes will alleviate pain, sickness and death, but he's apparently not a big believer in clinical trials and so winds up with a brain-eating zombie on his hands in the person of his nephew. The zombie even looks like one of those from "Re-animator," and in fact some of the make-up effects in "Serum" aren't bad. Unfortunately, the script is pretty slow and unbelievable in quite a few places, resulting in a soap opera feel for most of the first 3/4 of the movie. For some reason, the director feels compelled to tell us the time of day every few minutes by flashing it in big white letters across the screen. I can't see why this was important, other than being an attempt to provide viewers with a sense of time passing; sometimes, that wouldn't be present otherwise as the plot plods along.
There are a number of moments that just don't add up here. For instance, one victim is bludgeoned with a sledge hammer, but when we see the victim's head up close, there's no sign of that trauma. In another scene, a character runs down a fully lit hospital corridor (we can see the circles of light on the floor, in fact) with a flashlight in hand, looking for all the world like he's walking in the dark... but a moment later a second character walks down the same fully-lit corridor without one. These are just a couple of examples; moments of what look like directorial or editorial sloppiness crop up quite frequently throughout the movie.
"Serum" is better in some ways than much of what goes straight-to-video as independent horror lately. In terms of technical items sound and photography, for example it's got a more polished look than a lot of what lands on a DVD. On the other hand, there's still a good deal of wooden acting (particularly by one of the lead characters, the mad scientist himself!) and nonsensical moments that have nothing to do with suspension of disbelief and everything to do with writing and continuity. Maybe these are things that the people involved with making this film will eventually get more experience with, though. One of the problems with low-budget independent horror lately is that the filmmakers often set out to remake more popular movies that had bigger budgets, and that almost never works out. It didn't in the case of "Serum," anyhow.