Back in the comments on an earlier post, I asked Joe Clifford Faust whether he started out writing shorter works or novels when he was getting started writing. He turned this into an interesting blog post and I promptly forgot to mention it here. So I'm correcting that now. Check out Faust's post called Size Matters. He talks not only about his start in writing, but also the advantages and disadvantages to the different sizes of story. Here's a quote:
I know this belies all of our notions of bigger is better, but bigger is also harder, but that's the way it works with writing. Bigger is easier because the smaller you get, the more important each word becomes. It has to bear a greater weight, a greater burden, and must be sufficiently powerful to contribute in the most efficient way possible.
Therefore, at one end of the spectrum you have the novel, which allows you to stretch out with words, with story, with subplots and characters and place and theme. It's a leisurely walk in the park. Wordwise, then, a novel is easier to write than a play, which is easier than a short story, which is easier than poetry, which I suppose is easier to write than something like a tombstone epitaph. And note that by the time you get down to writing poems, you're the watchmaker, sweating over every word with a pair of tweezers and a jeweler's loupe, praying that what you're assembling will keep time and have the desired impact.
As for me, I'm still trying to work on short stories, though maybe I should go back and read my three Nanowrimo "novels" and see if there's anything salvageable from any of them. I'm thinking probably not, but it never hurts to look.