I have used 1 a couple of times with mixed results. I shot 1 buck with it and spooked 3. It all depends on the day and the deer.
I use one every so often with my stands on the edge of fields. I have had better luck with a doe decoy used during the heat of the rut than any other combintation. I have had bucks come into it and I have also had them never pay it any attention. As of now the only ones that have ever been spooked from it were ones that circled downwind. However, nearly every doe to come in contact with it circles it and blows out of the field. When it works, it is awesome. One of the first times I used it I had bucks cruising the field all morning, including a young buck that tried to make a little love to it.
I bought one late last year and didn't have any deer see it. One of my hunting buddies uses them relgiously and has had great results. I've seen deer come into his with their hair standing, head cocked and knock it over more than once...
Hell no they suck, just another gimmick to drag around and cloud your thinking. Yes on occasion they may work, but more times than not their useless. That's of course in my area and my personal experiences with using them. Don't like 'em, don't use 'em, and don't recommend 'em.
Later this season I'm going to use mine more. Last year I used it a couple times. The only deer to see it were a six point, ignored it really. A spike walked up to it and just stared and walked away and a button buck seen here in this video. Click Me What I want to see is a mature buck spotting him.
I had an old feather flex years ago and hated lugging it around, how much trouble is it setting one like that up. Looks good and all; from a distance especially, but looks like a headache to haul around. Not to mention packing a bow, climber, pack and some other things we carry.