We are advocates of reviewing books honestly.
Negative reviews? Fine.
Harsh reviews? Still fine. We've even posted some doozies ourselves.
Glowing fluffy reviews full of butterflies, rainbows and ass-kissing? Also cool.
Reviews based on a partial reading of the book? DNFs are fine with us. We've stopped reading a few books and written about why. But be prepared if people question your opinions based on a partial read.
Reviews that attack an author personally rather than discuss the book? We disapprove of that. Reviews should be about the writing. But if you act like jerk, be prepared for the results. Free speech means that you have the right to say something, not that that speech is without consequence.
We also generally frown on authors jumping in to defend their book or criticize reviewers. We know that negative comments can be hurtful and the Internet makes it oh-so-easy to respond, but really, just don't. Vent in private. Then smile and face the world. We'll think much much better of you for it.