Well I for one find it quite amusing. Shitheads and sociopaths get away in life with people not liking them constantly, and then get to surprise the people that don't know them every time, without even any help from the people wronged or angered by them before. Peeple would be the first thing besides self-destructive facebook pages that brings personal history into a modern system. History is meant to be learned from.
Sure, it can be abused to all hell. Decent people with even a hint of popularity will quickly draw spiteful reviews by the jealous or trollish. And I think it's worth it.
However, if it's opt-in it will be all but useless. Horrible people would just steer clear because there's nothing to be gained in the same way that walking into an electric fence leaves nothing to be gained. If they do it to pretend they're great, then someone posts too much negative shit, they just delete the profile, or abuse a remade profile. With endless libel suites, and no real upsides, this shit is probably dead-on-arrival.