It's niche but also designed for more than a single person to use at any one time, and so you shouldn't think of the pricing as "per person" but rather "per team / group / family".
As an aside, what I'd find useful is an app that pipes together mine and my friends RTM or Todo.ly or Wunderlist to-do lists so that when I add a task it also updates their accounts (I assume this is possible with the RTM api).
Per family pricing is a decent idea. We'll have to take a look at that!
Someone else mentioned integrating with apps that they use every day, so we might take a look into the various other to do products and see of we can build on top of them
As an aside, what I'd find useful is an app that pipes together mine and my friends RTM or Todo.ly or Wunderlist to-do lists so that when I add a task it also updates their accounts (I assume this is possible with the RTM api).
Keep up the good work though. Have fun with it!