One of our members practices Hapkido. She explained the basic philosophy behind Hapkido, and then went into more detail about the variation she practices called Combat Hapkido. This variation focuses specifically on its application to self-defense. She liked that the sport taught her to defend herself against much larger people.
Everything that she said about its style, however, sounded very similar to the other styles that we learned about. I did not find anything else particularly differentiating about Hapkido, though its possible that this may start to happen more often now that I am somewhat familiar with the many styles.