In the Wednesday round up Dear Author includes a mention of the expectations publishers and authors have of reviewers (the link to Mrs Giggles is interesting).

Um. I always thought a review was a gift, reader to reader with the occasional grateful author thrown in.

When people reviewed my romance novel, Guarded Hearts, I was incredibly grateful that a) they’d read it, and b) they found nice things to say. It was certainly not their “job” to spruik the novel or to hold back on negative criticism–although I’d have cried if anyone was nasty.

http://romancejunkiesreviews.com/artman/publish/contemporary/Guarded_Hearts.shtml
http://longandshortreviews.blogspot.com/2009/03/guarded-hearts-by-jenny-schwartz.html