Maybe its because I get profoundly high every time I watch Lebowski, but it took me several viewings to figure out that everything tied itself up quite nicely at the end. At least, questions of "why did things happen the way they did", were answered, anyway.
Questions like "what will happen to bunny" and "Will the dude decide he wants to play an active role in raising Maude's child" don't get answered because it really sucks the absurdity out of a movie to narrate the future of every character (unless, of course, you find a clever way to do it, ala Animal House.