Reviews do reflect opinions but also direct, measurable observations.
The trouble I am having with the ruling is that pesky old "reasonable" clause. The determination of a protected review and one that violates the right of the business owner because of falsehoods, will need to be reviewed on a case-by-case basis. 
I like this part: "whether the negative reviewer is presenting statements that are provably false."
If I say, "My 8 oz steak was 6 oz., I can prove that (or did they mean before cooking?). If I say, the service was slow, that is subjective. But if I say it took 45 minutes to be served, then one would hope it's an objective fact. 
I am still not sure if it is opinion or fact that "Hillary is a criminal" if she has not been convicted. (tongue in cheek).