Do ever wonder what the value of a review is? As an individual or as a publisher or author?
Reviews are opinions. Bottom line. At the very basic level all reviews of anything, whether books, games, movies, adult entertainment products...all opinion.
You may think "Well, some are more educated than others." or something akin to it. That is only barely true. Regarding novels, some reviewers may be able to comment about some things more often like "voice" or the tense used, but really, when it comes down to brass tacks, a review is a grade based on whether one person liked an item or not based on their preferences. While I may prefer certain things, someone else will prefer others. Millions of copies sold, every reader has a unique experience to a greater or lesser degree. I don't think that a review that goes in to why The Chapter's Due has better battle scenes and a truer feel than say... Dawn of War: Ascension is better or worse than one that blathers on about formatting issues, point of view shifts, narrative voice or any of that. makes no difference at all. Both equally valuable.
I think that the best a person can do with reviews is to find a reviewer who has a style you like, and consistent tastes. Doesn't even need to really be the same tastes as you. If Cletis the Review-Guy consistently likes what I don't...then I know if he just rips a book apart, I may dig it. Reviews put you in the ballpark of whether you'll like a book/ movie/ game or not.
Authors may get a bit more out of detailed assessments on voice, tense and plot points, but again, it really depends on the author. I do think that authors prefer a good review to a bad one, but a rant piece that is totally disrespectful usually drives away authors.
Some readers like their reviews like a tabloid: gritty and rank, full of rants and raves. Some like a conscientious evaluation: your mileage may vary.
For publishers, reviews are advertising. Even if the review isn't stellar, it still works on two levels: 1. many people know that their tastes are counter to the reviewer's tastes, so it still scores a net sale. 2. Consistently high reviews (or low ones really) show a marked bias. Who cares if the reviewer graded this book as an A+, he grades them all as A to A+. Meh. I think people appreciate a curve in their grading: not weighted heavily one way or another.
For authors and publishers both, reviews and sales indicate what people dig, and what they don't. A review saying "I was expecting X and got Y" or "There was too much of Z" are important. Publishers publish/ authors write what people want to (buy) read. They don't know if they aren't told. Sales numbers only tell half the story. A strong seller doesn't necessarily mean people loved it. It means people bought it. They may have hated it and that impacts further sales. Publishers are in business and they look forward, not just at the sales numbers.
For reviewers...reviews have an impact on sales. usually not taken by themselves, but in concert with other reviews as well as word of mouth. It's not enough to post a review anymore. You need to post a review, cross-post it to twitter and facebook, spam it to Goodreads, Amazon.com and Barnes and Noble as well as put a blurb on the publisher's website (if possible).
Talk with the authors. Build up a rapport with them. Help them improve by giving them good honest feedback. They'll help you understand what his story is trying to say when you misunderstand it (I know sometimes I just don't "get it"on some stories). Talk with the publishers, keep good contact with them. If you are writing a rough review, talk to them about it. Reviewers should try and be a part of a team trying to pimp out good material and helping to raise the bar in whatever is reviewed. Above all, try and remain professional.