Does anyone else use The Little Girl in Werewolf?
I have mostly played the game with this character, almost never without, so I can't really compare. That being said, from our experience as a group, and from my personal experience of having been The Little Girl myself quite often, this character actually isn't all that powerful, and certainly not "hugely overpowered". Whether I have seen the wolves or not, I still have just one vote, and I still have to defend it against others' views (with 10-15 people, our group is rather large). 

Of course, I can always say "listen up, people, I am the Little Girl, so follow my advice", but a) people don't have to believe me, since b) I might actually be lying, and most importantly, c) the wolves will pay special attention to me from then on, and I'll probably get killed the very next night.

Of course, The Little Girl does become quite powerful when she's also the Village Chief, but then again, so does pretty much any character. Besides, from our experience, a Village Chief is even more likely to get killed quickly. I would say the game is pretty well-balanced, actually.