First of all, this is not a serious vampire film. It is all fun, summer action flick that used to be one of the things that you could count on. It just hasn't been a case in recent years, but I'm glad that the trends are changing back from the series to movies. And as an August movie, Day Shift is perfect for chilling off in the Sunday afternoon, because you don't have to take it seriously.
Well, not in the terms of vampire knowledge, as it doesn't bring much new to the table, but it is bold on making it clear that the world in its own lore is a complete as it can be in the lore wise. Thing that they bring out is that there are four different species in this world: Southern, Eastern, Juvies and Elders. Without going into specifics, they're unique in their ways, and they keep the Elders as the top dogs, without mixing too many things into the soup.
Then there is the other side, vampire hunters and unionized vampire hunters. The latter holds a monopoly position in the "fang" market, trying at the same time to keep the undead as a secret even though the LA is full of them. It is on that side, where the protagonist Jamie Foxx gets help from a Union member, Snoop Dogg. After all, he's in a bit of a hole, for lying to his wife about the nature of his real job and therefore keeping secrets.
So the wife is going to leave the city in a week's time, if the boy doesn't come up with the money to keep the family in the LA. As a plot element it is a super thin and mostly on the shaking grounds, as it becomes clear very early on that the fangs has a price, depending on the age, and since the LA is full of them, you can make a very fine living if you're a fighter.
Thing is, the boy makes the ten grand bank within twenty minutes, just by bringing the fangs to the union shop and cashing them in. But he doesn't call his wife, as say I made it. Instead, he goes on a string of hits around the LA and by the film is ended, there's more than a hundred vamps on the ground, making the boy rolling in money, after he turns in the elder fangs.
But that is also the stupid thing, because he doesn't collect the fangs from all the kills. Instead, it is implied that he only took the most valuable, and left the rest. Another one is the chase across LA. Although gloriously filmed, with some aspects being from an FPV drone angle, it is also a cockup as it doesn't produce the law enforcement, even though there is public daylight shooting, explosions, crashes and bodies. It is as if this world is blind and deft on things that happen around it.
As a Hollywood movie, that is acceptable and if you take it as a such, this is a good one. Just turn your brains off and chill. Especially enjoy Snoop Dogg's shots, because he does some epic stuff, even though he ain't no Keanu Reeves. And for his involvement, I'm going to give this in IMDB scale 6/10.