I hate when a movie just sort of ends and is so open-ended you feel like it wasn't finished. I appreciate leaving things up to the interpretation of the audience and letting them make decisions about where things will go in the future - but the director has to make a decision; otherwise it is sort of a cop-out.
I think the toughest thing is to describe what a producer does because they basically do everything. They follow a project from the start through the rest of its life and, along the way, are a part of every single aspect of its growth. It's tremendously enriching, though, because you get to know and live with the movie in its entirety.