Yes, it is a serious burn rate, but we have three million users to maintain. That's why we are now just focused on our successful product. Wunderlist is a freemium product, we'll add premium features probably at the beginning of next year for a monthly subscription fee.
Do you expect those users to be sticky? The barrier to entry for making a to-do list is negligible, and having a long history of completed tasks is of very little value.
With Wunderlist we've already seen many repeat users and have daily users adding new tasks, especially during the week. With Wunderlist 2 we will have more features that will help grow this.
Fred Wilson wrote about user metrics, he called it the 30/10/10 rule (http://www.avc.com/a_vc/2011/07/301010.html) - 30% monthly active users, 10% daily active users and 10% new users each month. We can apply this rule to Wunderlist, but as we're in the 'task' market, we generally have more monthly users than daily users - because the product is more optimized for weekly use.
Sorry - I meant to clarify stickiness when asked to pay. Freemium conversion is like 1-5%, so I'd imagine somewhere closer to 1% with you guys.
With 30ish people, let's say you burn $2 million a year. You'd need to get 30,000 people to each pay ~$70 a year for your app. My numbers might be wrong, but I'm just curious how you'd get people to spend that when it's so easy to switch to another task app.