I really like it! The detail that you've applied to the shape of the land in relation to the water really makes it "pop" I would say. I'm a novice cartographer (I just started several days ago) so my opinion probably doesn't count for much, but I'd like to give some suggestions that you might want to try out that you might enjoy. Feel free to take these with a grain of salt.

Perhaps you could apply a slightly darker brown to the flat land areas that aren't green? You could use the colors>levels tool to add more of this color into the flat land, and then use a slight Gaussian blur to blend the color a bit better? This may or may not make it look nicer. Just something to play to see if you like.

Something about the red borders doesn't seem to fit for some reason. Maybe switch it to a black color? And play around with the opacity of that layer? That might look better.

Overall, this is really a lovely map. I like to forest texture. Did you use a bump map for that? Kudos from a fellow novice.