Plus you can ask for clarification in the forums, whereas reviews on those sites are static. Also, you get people who have a tiny problem and give one star saying "Crappy product, don't buy" or some such thing.
I'm not sure how much trouble it is to create new forums, but it would be interesting to see it on at least an experimental basis. It would definitely rely on tit for tat from forums members, but I think it could work.