Some good points that the review should be about the book, not the price or the format. But, for some people, the reviews are the only way they can make a point about pricing problems such as an ebook being priced higher than the paperback version.
Reviews are so subjective as to be nearly useless. I and my brother both read science fiction. He likes Jack L Chalker, and I am not a fan. I love Roger Zelazny's Amber series but my brother finds it just ok. Who's right? Me of course! Just kidding. The difference is a matter of taste.
I do sometimes look at aggregate reviews of a product, software program or app before I buy or download it as I do find that somewhat useful.
I don't think we were better off when professional reviewers were all we could read in newspapers and magazines because critics were notoriously wrong. Many times, a movie that critics panned became box office blockbusters. Critics often had an elitism or snobbery about books, feeling they should have some deep literary value - an approach that was useless in my favourite genres of science fiction and fantasy.