My first impression was that the map load is pretty wonky. I think you could use a loading image to make that look a bit better, but that's just a suggestion.

I'm not a fan of the green used for saved locations, it kind of hurts my eyes. Also, the sign up button that has text below it doesn't seem like those two things are together. It would make more sense to me if I got an error or something when trying to actually save a location.

When messing around in the app, I notice the error messages aren't particularly helpful. After I created an account and logged in, it wasn't very obvious that I was logged in.