Review my App: Park in the Shade

Forgive me if this is not the place for this. This is my first published app and I'm looking for some feedback.

First off, I know the graphics suck. I'm not a graphics designer. In bootstrapping this, I didn't have a budget for a designer. If anyone out there wishes to donate a mockup, that'd be great. Otherwise, I'm not going to tweak graphics too much.

I would like to expand the app into more functionality. I've got all the calculations needed to provide more information, but I don't want to overcomplicate things. Any ideas on what features I can start adding in? It's a pretty unique app, no real competition.

Thoughts?