I don't like the HOH idea ... never have ... especially if that person has some power which changes the nominations.
That said, I do think it works toward making that person's personality come out a bit more. The power may cause the person to show their true colours and "boss" people around, or perhaps the opposite and show a "nicer and more considerate" side of their personailty. In other words, being HOH can cause you to become even more hated (by HMs and the viewing public), or become even more liked (by HMs and the viewing public). And, with this in mind, I don't like the idea of it, but I can tolerate it if it has this kind of affect.