I'm still writing. I'm on track for 50,000 words, although it's only the one-fifth benchmark at midnight.
What's easy: I don't find writing 1667 words in a day that difficult. Even when I think I'm too tired I've managed it. On the other hand. I stop when I reach that goal, which could easily come back to bite me if anything happens this month -- like, say, hosting Thanksgiving (oh yeah, we're doing that). I have a rough story. The details that are part of my own life are easy.
What's hard: actually coming up with made up stuff is hard. Creating characters is hard. Creating a reasonable story arc is hard. Filling in the mystery's details is murderous.
Please wish me luck!