It is considered a vulgar or obscene word by many people, although this differs around the world and some people are happy to use it and hear it without offence. In Britain, it is often considered to be the one of most offensive words in the English language and may therefore be used effectively for humiliation.
The word is, like many pejorative words, being reclaimed from its former taboo status. The homosexual community has reclaimed the word queer in this sense over the last few decades. It may be that cunt will be seen in a quite different way in future.