What hundreds and hundreds of sites on the web provide are reviews. The reviewers talk about their experience of the film. They say little about the film as such, only about their feelings. They say things like, So-and-so gave a great performance or The cinematography was brilliant. I can’t translate that to anything about the film, only something about the way this person felt about the film. Evidently, the idea behind reviewing is that if the reviewer had a certain experience, then you will have the same experience. That is patently false. It is also not film criticism.
In my own mind I draw a sharp distinction between film reviewing and film criticism. I used to review films for WGBH-TV in Boston, long, long ago. The people who wrote in told me in no uncertain terms what a film reviewer is supposed to do. A film reviewer is supposed to tell you whether or not you want to see the film in question. Anything else is unimportant.
Reviewers may retell plots. They may make plus and minus statements about acting with (usually) no details. Manohla Dargis of The New York Times recently described writing about a film when you’ve seen it only once. “The easy stuff is usually the story . . . and characters . . . . The tricky part, when I get to scribbling, is everything else . . . . Was the lighting soft or hard, the editing fast or slow, the camera shaky or smooth, the acting broad or not?”
But most of all reviewers pronounce movies good or bad. Thumbs up, thumbs down. One star or four stars. In my own internet browsings, I am astonished at the number of people who set up shop as movie reviewers and choose to pass judgments and assume their judgments ought to define the way others feel about a movie.
Film criticism is an altogether different breed of cat (although a few reviewers, like James Agee or Roger Ebert, straddle the distinction). Film critics see films more than once. A good critic will point out a pattern in the action or details of shots or something special about the camera work. A critic studies a film in detail, to see it as a work of art. The critic doesn’t just look at broad categories like “lighting” or “editing.” 
Critics don’t concern themselves much with evaluation or recommendations. Some like to interpret films, to get at the "meaning" of the film (though I find that a confused concept). Some address film techniques and styles in considerable depth and sophistication. Some develop “theory.” You might take a look at the “senses of cinema” site for various types of good writing about film.
The film critics I respect most try to enhance their readers’ experience of the film by pointing out things of interest. That is what I try to do on this film site, A Sharper Focus. The name says it all. You will find far fewer films here than on reviewing sites, because you really have to work at serious criticism to get a sharper focus.
Behind the distinction between reviewers and critics, though, lies another, deeper issue. Are movies just entertainment or are they really an art form? It wasn’t until the late 1950s and early 1960s that people began to take movies seriously as art. Although there had been serious books about movies since Hugo Munsterberg’s The Photoplay in 1916, in the ‘50s more and more books like Arthur Knight’s The Liveliest Art (1957) made the case for Americans that had already been made by the Cahiers du Cinéma critics in France.
In the ‘60s and ‘70s films appeared on the market that clearly demanded that they be considered works of art. The Seventh Seal and La Dolce Vita drew a lot of puzzled commentary from newspaper reviewers, as did other films from Bergman, Fellini, Antonioni, Visconti, Godard, Resnais, and many another. And “film” (as opposed to “movies”) became an academic specialty. At the same time, in 1959, a 
handful of professors (including me) led by Robert Gessner of N.Y.U. created what was originally called the Society of Cinematologists. Today, its successor, the Society for Cinema and Media Studies, has hundreds of members and a huge annual conference. Film is big on campus, perhaps because students think it’s easier to see a movie than to read a book. Oh well.
As long as you think films are just entertainment--go to the theater, enjoy some laughs or thrills, go home and forget about it--then you want reviewers to tell you whether or not you’re likely to have a good time. Film reviews have a simple argument. The reviewer says I did (or I didn’t) enjoy this, and therefore you probably will too. It is, of course, false. We are all individuals. Just as we have unique senses of humor, so our likes and dislikes in entertainments (or works of arts) vary with our unique personalities.
So I really don’t care if Manohla Dargis or A. O. Scott or Anthony Lane had a good time at this movie. If I want to know whether I am likely to enjoy a movie or not, I go to the numbers on IMDb.com or RottenTomatoes.com, arrived at by tallying the likes and dislikes of thousands of moviegoers. They’re much more likely, to predict my reaction than a single reviewer’s take on a film. See my blog on this idea.
Are films entertainment or art, then? Wrong question! It isn't that this or that film is art or entertainment. It’s how you choose to look at a particular film. Are you treating it as simply a two hours’ pastime? Or are you trying to think about it seriously as you would a work of art?
Film reviewers, by and large, treat films as entertainment, and that’s what their readers want. Film critics, as opposed to reviewers, treat films as works of art, write about them as such, and encourage their readers to see films as art. That’s what I do on A Sharper Focus. I hope you will join me.