I haven't read through all the posts here, so forgive me if I am repeating something someone already discussed.
I have not tried out the program yet, but I'm watching the Basic overview video right now.
You asked for feedback.
A problem I have with most "mapping" software is they all seem to lack the ability to select and copy a region of a larger map. In photoshop, I make a large landmass (for world maps) and while I'm making the map, I create regions by creating a "shape" of the region. I add a new layer, select the entire landmass, then I remove the regions I don't need and I am left with the shape of one region. Then I fill that shape in with black and use it later to select only that region.
Once I have the shape, I can create a new document and move the one region shape to the new document, enlarge the shape (if needed), then I make a new map of the region.
Mapmaking software like Other World Mapper is great in a lot of ways, but I haven't found a way, with any software on the market, to duplicate the process (or similar) that I just described.
The idea is to be able to draw multiple versions of a map or parts of a map and not have to redraw the base land shape. Also, in Photoshop, I'm able to do "non-destructive" changes, trying out multiple techniques without losing anything or having to redraw anything.
Let me know if something like this is possible in Other World Mapper and I will buy it.
Otherwise, the app looks cool and useful. Good job.