In my time, I have written a lot of reviews, mostly of books and films, but occasionally of works in other media. I found that they were really helpful in working out my own artistic voice and esthetics; by writing about what did and didn’t work in other people’s art, I solidified in my mind what would and wouldn’t work in my own.
I generally called them as I saw them: if a book or movie wasn’t good, I would say so. (Although, even then, I would try to find something positive to say, since few works are truly irredeemable.) To me, a reviewer has a duty to be honest about a work under review; to be a critic, one must be critical.
I was surprised, therefore, when, as I started interacting with book bloggers to get my own books reviewed, I discovered a lot who would only publish positive reviews. If they didn’t like a book, they just wouldn’t write anything about it. (In fact, they would probably stop reading as soon as they realized they wouldn’t like the book.)
On the one hand, I get it. Most of them weren’t professional critics, they were doing it for love, and life was too short to waste on art they didn’t enjoy.
On the other hand, there are problems with this approach. For one thing, it’s good to promote books you like, but it’s also important to warn readers away from books that aren’t good. This is especially true if most reviewers are positive; a well argued opposing point of view could convince some potential readers not to waste their time on something they likely won’t enjoy, even though many reviewers did.
The occasional negative review is also important for the credibility of the reviewer. If you like everything, how can the reader of your reviews trust your judgment? (I think the same argument holds true if you trash everything.) It’s only by contrasting what you thought worked with what you thought didn’t work that readers of your reviews can get a good sense of whether they should trust your critical judgment.
As far as I can tell, my arguments fell on deaf ears. T’was ever thus…