I didn't buy one from that particular user but I did buy one off of ebay
sometime last year and I love it! I bought mine from this guy: Bitless Bridle Indian Hackamore Bosal TEAL BLUE - eBay (item 260701853913 end time Dec-31-10 22:16:05 PST)
He'll do custom colors and designs, it's great. Mine is glow-in-the-dark.
His are cheaper too. ;)
My horse is so much more responsive to it (she has some health issues that make it so she can't feel the bit) and I've never felt like I didn't have control. I have ridden other horses in it and I didn't like a few of them responded, but not every horse likes going bitless. Also, I think that, at least the kind I bought, the nose kind of conforms to the horse's nose (it's kind of a stiffer thin plastic-y sort of rope) so it might not be the right shape for another horse.
I'm really happy with the one I have. I've even put it through the washing machine and it came out fine. I use it on an almost daily basis and I'm more satisfied with it than any bit I've ridden in (at least for my mare). I fully plan to buy another one in a year or so.