So here's something very similar i launched recently http://www.knowcase.com (works on ipad & mobile too)
I watched the workflowy video in the article, thought "meh". Then I came back to HN to read the comments, and clicked on your app. Tried the demo, got intimidated by the interface and left. Came back to HN to read more comments, decided to check out workflowy's site afterall. A simple sign up, validation from Matt Cutts, and the fact that its a YC company persuaded me to give it a try.
tl;dr - Validation does matter. Convince the people who your target market trusts, and the rest will follow.
You might want to take screenshots of a few use cases, skitch them up and post that on a more....link for those who want to learn more.