Werewolves are an interesting breed of monster (and I don’t just say that because I’m a dog-person rather than a cat-person). The idea of an uncontrollable beast within makes for a captivating hook to hang a story from. The notion that unnatural powers can be like an affliction that the bearer may not even be aware of.
A werewolf that can change at will is less appealing to me as a reader or movie watcher. Just like The Incredible Hulk comics lose their excitement if Doctor Banner can change whenever he chooses – there’s just no tension.
Unlike vampires, which have steadily lost all their traditional weakness in modern fiction, werewolves are still typically stopped in their tracks by silver bullets. Whether this kills just the beast or also the man is up to the teller of the tale. When the moon is full in the sky, I still keep an ear out for distant howls. Just in case.