You can use the same criteria for a novel, play or short story and apply it when evaluating a film. Such aspects as setting, characters, plot or intrigue, symbolism and themes all need to be considered.
As mentioned in the previous comment, a basic knowledge of film-making and film jargon (terms) is needed as well. This is especially true when considering the way a scene is shot (for example, a close range as opposed to a stock shot) and the manner in which it is "set" into the rest of the fillm. Is a scene suddenly there or does it fade or in or out?
A good source of study is Gore Vidal's television play "Visit to a Small Planet" in the MacMillan edition Insights into Literature since a glossary of such terms is provided.
Film criticism is when you use the different elements of fim-making, and your own reaction and opinion to analyze the quality of a film. The analysis of your opinion or reaction, and how you feel other people will react to the film is something that anyone can do. Did you like it? Why or why not? Do you feel that others will like it? How does it compare to other films in that genre? Does it meet expectations?
For the other part of film criticism, it is handy to know a bit about the art of filmmaking. To do this, I recommend taking an Introduction to Film class at a college level, or ordering a film textbook to peruse yourself. There are different categories of expertise within filmmaking: directing, acting, producing, cinematography, acting, editing, music and sound, special effects, script and storyline, location, set, costumes, make-up, stunts, etc. To analyze a film, it is handy to be familiar with at least the basics of these elements in order to more intelligently analyze how the film did in these areas.
I hope that gives you a general idea. To find film criticism try yahoo in their movie section, or rottontomatoes.com. I've also provided a couple links below.
I agree with the above posts which list the technical aspects of film-making that a critic can examine. But aswell as these 'crafts', there is also 'the art'. The acting, photography, script, music etc, go together to make a piece of cinematic art that can be clever, moving, funny, political and so on.
It is the critics job to catch the meaning of the film. To see its plot and sub-plot. To feel for it's characters. To learn and experience the things the film is trying to communicate. Your intellectual and emotional reaction to the film and its 'concept' are perhaps the most central aspect of criticising a film. This can be as simple as,
"I really liked it." "It was beautiful." "I felt sorry for the main character." "The story wasn't believable."
or as complex as
"Setting the film in a mundane shoe-factory counter-pointed the surrealism of the underlying message that beauty and salvation are found in unconditional love."