I have won NaNoWriMo twice. It accomplishes basically nothing. It's the writing equivalent of running a supermarathon. It's a stunt, something you do to prove that you can.
You won't improve at writing because learning requires self reflection and you don't have time for that. You won't progress a stalled project because it can't address the reasons you're blocked and it's not an environment that will produce something usable.
It can be fun, or cathartic, just like running a supermarathon is for some people. But what made me increasingly queasy about it is exactly the way that the organization and the community sort of promote the idea of it as a learning experience, or worse, a career thing. It's really, really not.
