Great app, I like it, but I did notice some problems:

My city is comprised of several islands, and there's relatively large bodies of water between them (over 100 metres), but this map shows those large water bodies as narrow (1 or 2 metre) river-like things.

I understand this might be the problem of the underlying data source, and not the app itself.

(For what it's worth, both Google and Apple maps correctly displays the islands and water bodies).