From my experience I believe, when used properly, it can help decrease but not completely mask human odor.
I use Scent Lok but I still play the wind when possible. If a deer ends up downwind, I'm praying my scent dispersion is minimized enough that I do not get busted. The suit is just part of my scent "minimization" process. So does it work? For me, I believe it does what I ask it to.
I'll be writing a blog dedicate to about scent elimination this season. Keep an eye out for it.