I tried one and hated it... the electric pulses felt icky and it hurt me a couple of times. I also hated the pads on my back. I still ended up with a drug free labour.
My sister swore by it when she used one though.
This is why I thinks it's essential to try it before you make a decision as to whether to use it. I could tell straight away that it would be a great thing for me, but for others the sensation will be unpleasant.

Odette - Where in Melb do you live? I hired mine from a company in East Brighton and thought the guy who showed it to me was great - they do send them out but as I posted above I think a "go" of it first is better. I will PM you the details if you want - let me know. It depends on the hospital you are planning to give birth in as to where you can hire them through - this company I went through were fine for Royal Womens/FPH and Masada as there are the 2 hossies I've dealt with. (ETA : Ahh, I see you are in Montmorency so East Brighton not so great - ask your hospital).