There were couple of points he attributed to the success.

1) Eyecandy (he said it is 50% of the battle, on iphone people love eyecandy) 2) Getting genuine reviews on the blogs which allowed the app to go viral 3) Make an app for yourself, if it helps you getting something done and you can't live without it, others may also find it useful.

You should "tell hn" about your app and "ask hn" for some thoughts, ideas. Congratulations on shipping the app.