Nice work, for your first map this is mighty fine! However, I see some river violations. On both the souteast and northwest areas you have rivers that split in two before reaching the sea, unless its artificial or at a river delta this doesn't happen naturally (River Police please feel free to stop me if I'm wrong). My other critique is that you might want to lower the opacity on the shadows you have on the continental shelf, its a bit too stark at the moment. Just my thoughts.

-D-