Once I got it it up and did the first little bit of marketing, it's been literally no work. Maybe 30-45 min a month answering questions, but I wouldn't consider that work. :)
It's definitely worth it if you have the time to do it well. I know one instructor who did $140k in his first month (he did have an audience beforehand though). Feels like a 'goldrushy' time in online education right now. A lot of people don't know this.