There are two audiences you can sell to online with review style sites.
The best audience to target with this form of article marketing are google searchers looking for reviews of the products they are almost certain they want to purchase. All you have to do once you manage to get this audience to your pages is show them the benefits of your product and sell the solutions it can provide.
The reason this strategy doesn't work when you attract a different audience, those who are still trying to figure out which product they wish to buy, is that they are looking for understanding their problems before purchasing. They will read your page and move on to the next because they are not ready to purchase just yet and want to learn more first.
So who are you targeting and how will you get them to click on your links?
If you are targeting the first group of ready to go buyers that just need a little kick to get started, all you have to do is reassure them that they have made the right decision and link to a purchasing page. However, if you are targeting the second group, you will want to provide reviews of multiple products but make sure that one of them gets the best review so your readers have the illusion of choice. Obviously they will pick your best review, but show them that you are giving them options and other products to compare this choice to.
So, who are you targeting and how will you target them?