I'm 95% sure of something I'm considering on buying before I ever see any reviews. I think if used properly they can be a useful tool for brand exposure. In that regard, reviews can sometimes be helpful with things like lume longevity through a war lineup. Information about bezel alignment, feel and issues with new, untested features like on-the-fly-micro adjustable clasp are useful as well.
IMO reviews for exposure seems to have helped grow certain brands. Obviously, Zelos is one of the more successful micros so in that regard, mileage may vary. Recently production on the core models was increased because of selling out in minutes. That has seemed to help with the frustration of potential customers trying to beat the clock to buy something, but missing it. IMO it has helped to discouraged scalpers.
I'll be honest, Marc isn't exactly totally forthcoming when it comes to some of the features on his trinkets. I've been disappointed in the longevity of the lume compared to other brands. In the videos you would think they would be real torches the way they are hawked about the lume brightness. That is one of the pitfalls of someone reviewing their own brand. Something that has their name on it isn't likely to be bashed with any negatives.