This is a similar concept to PayPerPost, which recently received venture capital, and also has come under fire in the blog world for it’s concept and lack of transparency, although they are supposedly making some changes to their model.
ReviewMe is setting it up well, as the advertiser is only paying for the review, not necessarily a positive one. The blogger also does not have to link to the advertiser, it can just be a review. They are taking a very ethical stance which is great.
I do think though that this is probably still a pretty niche play. Even if the blogger has the right to do a positive or negative review, they still have to disclose they are doing a paid review. There are a lot of bloggers who are not going to want to do paid reviews at all, and if they did they might not want to admit it for fear of losing credibility with your audience.
On the flip side though, this isn’t that much different from reviewing a product and providing an affiliate link, which many bloggers have been doing for ages. It should be interesting to watch, and I’m all for anything that provides web publishers a way to generate more revenue from creating sites about their interests and passions.