I really like how you use the bank icon as part of the MKAnnotation you place on the map. It's a really nice visual tweak.
Only four reviews.
Sadly, I think the majority of low star reviews do not have an actual text review associated with the rating because it's so easy to knee-jerk dismiss the on-uninstall dialog with a low rating.
Perhaps it would be helpful if Apple forced a radio button dialog - why this 1 star rating (e.g. list a few choices - crashes, doesn't run, etc.)
Have you tried correlating your 1-star ratings with the crash reports on iTunes Connect? This is assuming the rating has a date (which it sadly may not).
Downloading it now to check it out/do some testing.