Externally, Yuuzhan Vong resemble humans to a degree, but they are distinguished by their sloped foreheads, grey-and-yellow skin, and short noses.
Masochism is a common element throughout Yuuzhan Vong culture, and headscars are considered a symbol of rank in their society.
Their hatred for technology originally came from the fact that they were, before they became a villain race, caught in the cross-fire between a war between two races of droids.
Yuuzhan Vong society is highly religious and is divided into a number of castes -- including Warrior, Priest, Shaper (Genetic Engineer) and Intendant -- each with its own culture and its own gods.
In general, the fan reaction to the Yuuzhan Vong has been negative, largely because of biowank.
Yuuzhan Vong entry in the StarWars.com databank