Downloaded the app, first screens look good. I would definitely use something like this, living near a huge park in a big city, and being very active. However:

- I don't have Facebook, how do I create an account?

- Do you really, really need accounts at all? And if you do, can't you at least just show me activities happening around me, and let me sign up later?

I'd love to give more feedback but I'm stuck outside your app.