I go back and forth on this. I support having user reviews 100%, and would love a forum dedicated to just that.
However, I go back and forth about how much I'd be able to contribute. Really having to tighten my belt in regards to spending, and I'm finding that more lately I just don't care enough to write any reviews. Sometimes I'm in the mood, and would love to, but don't have anything really review-worthy.
Other times when I do, I've spent so much time installing the new hardware or doing whatever that I don't want to bother writting up a review- just want to enjoy the new item.
Brutally honest, I know- but I'm not gonna' lie about it.
As to the forum in general, absolutely for it and would love to read other's write-ups on products. Might even inspire me.