No insult meant, but you lsot me at the home screen. The first thing you do is ask for sign up or login.... I have no idea how your app works whether ill want to visit it again or whether I even trust you, so I'm not going to start my experience by giving you info.

I see a lot of sites make this mistake. If you can't put people right into the functionality of the app so that they can play with it themselves, then give them a search box or at least tour of the app, epmhasising that it is free, to entice them to create an account.