Richard Schickel defends professional critics in the LA Times:
Criticism — and its humble cousin, reviewing — is not a democratic activity. It is, or should be, an elite enterprise, ideally undertaken by individuals who bring something to the party beyond their hasty, instinctive opinions of a book (or any other cultural object). It is work that requires disciplined taste, historical and theoretical knowledge and a fairly deep sense of the author's (or filmmaker's or painter's) entire body of work, among other qualities.
Opinion — thumbs up, thumbs down — is the least important aspect of reviewing. Very often, in the best reviews, opinion is conveyed without a judgmental word being spoken, because the review's highest business is to initiate intelligent dialogue about the work in question, beginning a discussion that, in some cases, will persist down the years, even down the centuries... I don't think it's impossible for bloggers to write intelligent reviews. I do think, however, that a simple "love" of reading (or movie-going or whatever) is an insufficient qualification for the job. That way often leads to cultishness (see the currently inflated reputations of Philip K. Dick or Cornell Woolrich, both easy reads for lazy, word-addicted minds).
And we have to find in the work of reviewers something more than idle opinion-mongering. We need to see something other than flash, egotism and self-importance. We need to see their credentials. And they need to prove, not merely assert, their right to an opinion.
I don't think anyone has to do anything to prove the right to an opinion and I certainly don't believe credentials are anything but incidental to a critc's value or qualifications. I believe that we prove (or don't prove) ourselves with every word we write. I loved seeing Dana Stevens move from a blog to writing for Slate and the New York Times. But she did that exclusively on the basis of her writing, not her credentials (which happen to include a PhD, but not in film). One of the greatest columnists of the 20th century was Mike Royko, who used to drive a cab until one of his passengers happened to be a newspaper editor and offered him a job at the paper. I do agree that the recommendation is not the most important part of the review and that a good review requires more than a love for movies (or books or whatever) and the impulse to express one's feelings is not enough. What matters is strong, involving writing grounded in full engagement with the subject of the review and enough understanding to appreciate its context.