Maybe this is a common marketing technique, but I had (and still have) no idea what the site does. "reinventing teamwork" sounds interesting, yet it still doesn't tell me much. Don't get me wrong; I do appreciate the minimalism. However, you're asked to enter quite a bit of information before you know why.

One alternative is to start the user out with sample projects and tasks (like Trello does).

One other thing: the "invalid password" message when creating an account is not very helpful.