Do realize that in some countries the "gift" of a product for review is a paid advertisement, and must be noted as such in any advertising (including the web). Tread carefully. Product endorsement is a well-recognized method of marketing around the world, and failure to reveal free product for a review might be criminal in some countries. Ordinary endorsements (ie, the reviewer independently purchased the product and then reviews) are quite proper and welcome.
Arrgh! Back to edit as I know the above sounded harsh.
If you are looking to try a new product to find out how it might market/sell in the real world, I stick with my first comment: Go local. Walk the streets of your town with the product and ask some folks to try it out. Get that feedback, see how it turns out, then do a different presentation to further expand the introduction of product to the market.
Open a website, allow commentary (much like yelp, only it is your site) to gain additional information. Develop a marketing/advertising plan and move forward from there.
This will take some time. It does not happen over night. All the caveats mentioned above still apply. You can't give something away for a review which is then used as an advertisement UNLESS you mark it as a PAID ADVERTISEMENT. YOU CAN give stuff away to see if people like it. That is okay.