Well, you get unhelpful comments like "pretty good"... because it looks good. 200 dpi at paperback size -- I bet a lot of the beauty gets lost. The fine forest detail will probably turn to mud. One thought - the reason for your light water, dark land is to immediately tell the two apart, right? Well since your places of interest are mostly on land, why don't you flip it? Dark lettering and symbology against light land would get you better contrast.

A further possibility would be to make two versions. Go simpler, starker for print, and indulge yourself with color and additional detail in a version of any resolution and complexity you like, online. Annotate the in-book one with your URL, promising 'additional detail at the website'. A side benefit would be a modest stream of readers hitting the site on into the future, where they can of course find out about further books by you :-). Heck, make it a community, where the readers' most frequently asked questions get answered in future stories.

Ymmv - I am neither a publisher nor a published author. But I would sure hunt down added info online ... in fact I have. :-)