I never hunt without it. I killed my target buck back in 2019 after he came from a completely wrong direction. Walked right through my scent stream, stopped in his tracks, took two steps backwards, then decided it was ok to walk into the plot. It DOES work. BUT it is not an invisibility cloak like the commercials would like you to believe.
Some deer dont care about it all, they will sit there in the scent cone getting blasted with it and not have a worry. Other deer will get a little weird over it but eventually calm down. And some deer will freak the heck out. BUT they do not typically blow like they would if they smelled you, they just get weirded out by the foreign scent.
There is also a right a wrong way to use it. It will not work great in high winds at all. In a blind its nearly unfair for the deer because it does work so good in a contained area. The best time you use it in a tree is when you have a sustained wind between 5-10 mph.
You must have realistic expectations with it. Does it work YES, will you be able to fool every deer NO. Do you still need to hunt the wind, OF COURSE. Using basic scent control is important as well, but using an Ozonics unit correctly might just help you fool the deer your after.