First off, Mexican Werewolf in Texas' title is misleading as many others have pointed out. It is actually about El Chupacabra, which is a similar creature to a werewolf, but by no means the same.
The production and editing just plain suck. When it was over, I probably wouldn't be able to give a very accurate description of what exactly the Chupacabra looked like, for whenever it was in a scene(despite one or two exceptions) the camera turned all shaky and you could only see the monster's face clearly. The special effects were laughably bad, but that has to be expected from a low budget horror movie.
Along with the terrible production comes the bad actors. Now a couple give fairly plausible performances(Erika Fay and Martine Hughes), but then there were the bad actors(everybody else), who seemed to have no emotions whatsoever when people died. Then there's the absolutely terrible actor(Sara Erikson), who gives one of the 2 worst performances I've ever seen in a movie. I mean my god, she was indescribably bad.
The plot was very simple. Basically, a Chupacabra is in a small Texan town killing off local residents and a group of teens look to stop it. However, even with the plot being this simple, a few plot holes managed to leak through.
Anyways, horrible movie. However, if you are looking for a movie to make fun of and laugh at with your friends one night, this would be a pretty good one. My friends and I had a good time watching this. Probably the 2nd worst movie I've ever seen, 1/10. Awful.