Ronald Bergan wrote a post at the Guardian titled "What every film critic must know."
...it seems that film, the most accessible and popular art form, is just not treated on the same level or with the same degree of seriousness as the other arts.
Unfortunately, this has led to a deterioration in film criticism, which has become primarily descriptive, anecdotal and subjectively evaluative rather than analytical. Most reviewers deal primarily with the content of a film - anybody can tell you what a film is about - rather than the style, because they do not have the necessary knowledge to do so.
He goes on to list what he believes every film critic should know (difference between a fill a key light, e.g.), have read (Eisenstein's The Film Sense, for one), or seen (Jean-Luc Godard's Histoire(s) du Cinéma). The good thing is, I should be qualified to be a film critic by the time I graduate film school if other avenues don't work out. The comments on Bergan's post are, as expected, heated. I think his requirements are too extensive, but I tend to agree with him more than I disagree.
I don't read as much film criticism as I once did. One reason is that few critics write well enough that their reviews are enjoyable to read as just pieces of writing. Another reason is what Bergan notes about reviews becoming too descriptive. A third reason is that it's difficult to find a reviewer whose tastes match well enough with your own that their opinions can serve as positive leading indicators (though a great reviewer can educate even when you disagree with them). I also enjoy seeing movies fresh, and I'm not just talking about spoiler-free. Having someone's opinion in my brain can subconsciously push me towards agreement or disagreement even before I've seen the movie.
I also don't watch as many movies in theaters as I used to. With so many classic movies now available on DVD, there's greater competition for my entertainment consumption, and I've seen so many movies that I'm suffering from severe Hollywood fatigue.
One worthwhile type of film criticism, to me, is the review that articulates why I feel a certain way about a movie. Some of Bergan's requirements about film stylistic techniques are helpful in this regard, but Pauline Kael provided many of those mini epiphanies and I never thought of her as a very technical film critic. Much of film influences us subconsciously, but having stylistic choices brought to my attention doesn't detract from the effect, it only enhances my appreciation of the filmmakers' craft. I took a class in fall quarter of film style in which we watched one movie a week and discussed the stylistic choices in a particular area, for example in editing or camera movement or story structure. It was one of the most instructive classes I've ever taken and made me aware of how rare good film style criticism is these days.
Lone contrarian voices in a sea of agreement catch my attention as well, though only if they're critics who seem to know something about film. I'm naturally attracted to contrarian opinions. Consensus among a broad group of critics that a movie is terrible or great will pique my curiosity; the former is usually a decent sign that a movie is, indeed, awful, while the latter seems to throw down a gauntlet. I can't help but see what the commotion is all about.
I've met perhaps five people in my life whose opinions about movies always interest me, but I can't remember who two of them are.
But despite the somewhat depressing state of film criticism, I still find it far more useful than music or book criticism. I don't understand enough about music, but most music criticism seems to me purely subjective. At the end of the day, what most matters to me when reading a review is to feel as if an intelligent mind is grappling with their reactions to a piece of art and sharing their revelations.