Interesting idea - in a similar space to my startup http://www.happybuy.com/

It may be good if the site was able to, based upon the metadata and extraction from the product description, show the relative differences in the specs of the products.

For instance, if I compare a Macbook 13" and a Macbook Pro 15" it would be great if it listed all of the differences - such as screen size: 2", price: $300, speed: 0.4Ghz, weight: 700gms, popularity: 200 difference in sales rank etc.

It would allow objective comparisons to go along with the subjective comparisons of the reviews you currently show.