I agree, Kelly. If I find a product that I am completely unhappy with, the chances are that I won't waste the time it takes to write a review on it anyway. I'd rather use that time writing a letter to the manufacturer. That said, I would have no problems making a post about it in the forums just to warn other members to stay away from it.
I wouldn't have a problem posting a less than favorable review on a particular product, so long as the review was fair, objective, and respectful. Words have meanings, and the way words are put together with each other can make all the difference in the world.

There is no review worth having legal problems over, IMO.