Perfect, I am at this exact spot! My startup launched and we got around 100 signups, but none of them are coming back. I guess I should push hard to really talk to as many as I can.
Thanks for putting new context on the lean startup methods.
You should also read "The Lean Startup: How Today's Entrepreneurs Use Continuous Innovation to Create Radically Successful Businesses" [1]. This will give you a guide to metrics you should be using to track your status.