I was originally looking for just the first film in this series when I saw this boxed set and probably wouldn't have bought the other two films if I had seen them individually. Having said that, however, I did enjoy all of the films and anyone who enjoyed the first one will probably enjoy all three.
The first film, John Carpenter's Vampires, is by far the best of the three following the remains of a team of vampire slayers funded by the Catholic Church who were slaughtered by an extremely powerful master vampire. Accompanied by a rookie priest and a prostitute who is in the process of tuning into a vampire, the slayers must track down the master vampire and stop his plans that would see him become almost unstoppable. Not a masterpiece by any standard this first film is enjoyable, however and most vampire fans would enjoy it.
Vampire: Los Muertos on the other hand is not really that good and although it does have a few good ideas few of them are all developed fully and some of the acting is quite poor. This film is a follow on from the first with another master vampire trying to do what the first one failed to do. Trying to stop her is a ragtag group of slayers lead by a freelance slayer played by Jon Bon Jovi. This film is definitely the worst of the three.
The final film, Vampires: The Tuning is quite good. Moving the action to Thailand, the film has little in common with the other two in the boxed set, despite having the same feel to it. The Turning sees an American tourist getting caught up in a war between two groups of vampires, one good the other bad, when his girlfriend is bitten and abducted by Niran, leader of the evil vampires. This film is surprisingly enjoyable with a mixture of western and eastern vampire myth with a smattering of martial arts thrown in. The idea of having the film from the point of view of the tourist rather than that of the slayers or vampires is interesting and works reasonably well.
Al together these three films are well worth watching, although there are quite a few poor bits in them, most of them in the middle film.