it works really well with our Millie and we also had the problem of her needing a wee really bad at 3 in the morning EVERY Morning!! she used to wake up and just go on the bed or on the carpet by the door which as you understand isnt great at anytime never mind at 3am!!!
we managed to teach her that if she wants a wee, she wakes one of us up and we will let her out. shes doing really well with this at the moment which is good!!!