Reached page 55 today so I'm over half way to my goal of 100 pages by the end of the month. A screenplay certainly utilizes a different set of writing muscles than a novel -- much more dialogue than description, no internal monologues, present tense rather than past -- that sort of thing. In general, I'm finding it "easier" as long as I remember to keep the writing uncomplicated and to the point. No room in a screenplay for the kind of richly descriptive writing that you need to do in a novel. Economy is the watchword when writing for the silver screen.
That being said, it still has to be an entertaining enough read that the script readers will want to send it up the food chain. After all, what screenwriter doesn't dream of seeing his script produced?