I think you should use softer brushes where textures are concerned. Around the edges, the change is too sharp and drastic in most cases. I think particularly where it comes to the edges of mountains, and the sort of underwater 'continents'. For my personal taste, I might add some brown around the bases of the mountains or something like that. Going straight to solid grey/black is a little too stark for me. But again, that's personal taste.

I like the detail in your rivers - you did a great job expanding that, though it looks like you changed the color of them? Anyway, I like the overall map. There's plenty to explore, for sure.