Obviously, if you don't like horror movies, then you won't like The Ruins. However, if you enjoy the genre, then this film is above average. Its strength as a horror film is its ability to allow the audience to identify with the characters and situation. The characters are young people in their early twenties, from American and European middle class backgrounds, who meet up by chance in a Mexican holiday resort and decide to have an adventurous exploration of some Mayan ruins. The horror of the film is not that they run into some kind of supernatural or alien terror, but basically a predatory carnivorous plant, in this case, vines. It is like a giant Venus Fly Trap that eats people, but also has a parasitic ability to grow within its victim's body.
The film does a fine job developing the characters, each having his or her own unique disposition. In fact, the characters in this film add to the horror effect of this film in that they are genuine and real people with a strong sense of looking out for each other. There are no jerks in this group, as you often find in such films, so that the audience can be emotionally indifferent to their demise. There is a certain emotional power to this film as we view these average young people, used to the security and comfort of their backgrounds, finding themselves alone in a nightmare that they are slowly beginning to realize will ultimately lead to their death.
This is a horror film that I can safely say does its job in giving the viewer the chills.