I've know about it, but never got the chance to sit and watch it. Like most shows on Showtime, I'm pretty late on getting to watch them.
Then again. I prefer waiting for the entire season to be available, so I can watch it all at once instead of waiting week after week. Unless it's Heroes.
Uhm...not sure. Could be Quinn, but I always hope for someone closer to the cast to be a killer. Like, I would have liked it if Rita secretly killed people. But then after watching episode after episode, it felt wrong. So I'm glad it never happened.