The clusterfuck that is the current Zon review system was something I blogged about last year, though that was more about encouraging people to go ahead and leave a review of a book they loved – or hated. But there’s been another flurry of review-pulling and even reviewer-banning, to the extent that the Erotic Authors Guild has been trying to address the matter.
Reviewing is a hugely underrated artform nowadays, especially when it comes to, well, the arts. A good reviewer knows how to give all the relevant information without too many spoilers, rates whatever it is according to a range of factors (is it fairly priced? Has enough care and attention been given to the item/product/experience before money is charged? Is it what you might reasonably expect it to be given the description/promotion?) and does so in a way that’s interesting and entertaining, even if the product or service in question is not something the person reading the review is all that likely to consume.
It used to be the case that a skilled, experienced and fair reviewer was valued to the point of being properly paid for their work. The free stuff you got (books, food, music, event tickets) was a necessary perk in that you needed to access stuff to write about it, but the work you did in writing the review was paid for by the publication where your review appeared.
Yes, there were drawbacks to this, particularly in terms of the limits on how many great (or terrible) things could be reviewed per month – and the business-as-usual fact that most of what got reviewed by 
way of books, films and music, was the output of people who were male, white or both. More reviewers out there is more likely to mean a greater diversity of product reviewing, and a chance for smaller-scale or newer writers from a wider range of backgrounds to attract attention.
However, Amazon’s current objection to the idea of any publisher (whether trad or indie) sending advance review copies to a few book bloggers and reviewers they admire or trust… well, that is a massive mistake. An active book reviewer, who loves and understands books, is going to write reviews that are far more considered, interesting and ultimately helpful to the potential buyer than half a dozen random idiots who can’t even work out how the star rating functions.