I am often asked what criteria I use to evaluate screenplays in order to determine whether or not to recommend them. I don’t have a strict rubric or anything, but there are definitely things that I pay attention to and they are as follows:
First and foremost, the script has to be interesting. It has to be about a subject that I’ve never seen done before or else, if it's about a familiar topic or genre, then it can’t be by-the-numbers -- it has to introduce some new twist to the piece that is not completely predictable. And the script needs to be interesting from the get-go -- something intriguing (an attention-grabbing incident, a compelling piece of character-revealing business, etc.) needs to occur in the first scene and preferably on the first page, because if a script doesn’t grab me from the moment it begins, I’m going to quickly lose interest and tune out way before I ever get to that really cool scene on page 54.
I have to care about the protagonist. This doesn’t necessarily mean that I always have to like the protagonist, but I do need to understand him and have some degree of sympathy for his motives and goals. (This is especially important if you’re going to do a story about a bad or unsavory person that sees the light in some fashion. Such tales can be inspiring, but by definition, you have to begin the script with the character doing some sort of terrible things. If you don’t give me a reason to connect with such a person, then I’m not going to care when he has his eventual epiphany.) I don’t require the protagonists or supporting characters in every script I read to be three-dimensional (because not every type of film -- broad comedies, for example -- require their people to have great depth or multi-faceted personalities), but they do need to be lively and interesting, with compelling traits and quirks (although, with very rare exception, self-consciously “quirky” characters are usually a turn-off), habits, points-of-view, and senses of humor that bring them vibrantly to life.
The script has to be cinematic. The story has to be told through a combination of images, action, and dialogue (with the speeches serving to enhance and provide counterpoint to the bits and pictures) rather than be told though dialogue alone -- a script can’t just consist of a bunch of scenes of people sitting around talking.
The script has to be what it is -- if it is identified as being a comedy, then it needs to be funny; if it’s intended to be a horror film, then it needs to be scary; if it’s a thriller or an action film, then it needs to be exciting.
Finally, and most importantly … I feel something at the end. If I reach the end of a script and find myself experiencing an extremely powerful emotion of some sort -- if I’m smiling broadly because things have worked out well for a character that I care about; if my sides ache because I have been laughing so hard; if I am weeping because something profoundly moving or sad has occurred in the story; or if I am feeling any other feeling for any other reason -- then the chances are pretty good that I am going to recommend that script. If mere words on paper can provoke such a powerful response, then those same words brought to life on screen are bound to have an even greater impact on audiences. Not many screenplays can accomplish this and, since moving an audience is ultimately the point of all this, any script that can certainly deserves (and will get) my support.
I care about other stuff too -- the dialogue should be good, and I like it when scripts are properly formatted and use correct screenplay terminology and when the spelling, punctuation, and grammar are all mostly proper (because such things show that the writers care enough to be professional, which means that all of the other elements of the script are probably going to be equally polished). However, none of these things are deal-breakers for me because better dialogue and correct spelling and formatting and such can always be added -- heart and feeling can’t be.