I have had one for about 7 years and have used it in conditions down to -10 deg. It works great, really extending those cold weather hunts far beyond the time I could handle with normal cold weather clothing. When it gets extremely cold, I drop a couple of those heater packs in the suit and I am toasty warm. My circulation in my feet isn't that great, so my feet usually go pretty quickly, the suit has virtually eliminated that problem.
I have never been busted by unzipping the suit, and with strap system it uses, the suit is pulled behind you,out of the way. They are kinda spendy, but it is the best solution I have found.