I like this too. I really don't have a problem with the "blurring' around the coast at all. It matches the rest of the pallet if you ask me. I also agree with torstan on his comments. I would suggest that next time you use this style, that you use a line at least half as thick (maybe only double the line weight of the mountains) and maybe not so dark, maybe more grey than black. In either the Tutorial or How Do I forums there is a sticky on how to properly place your rivers. Makes for a good read IMO.
As a primer, think of rivers as trees, the ground the sea, and then look at all the branches. You will notice that the branches are more numerous and thinner the further away they are from the ground. Most branches also join their supporting member at a gentle angle or at least less than 90degrees. Most of the time. Not always. But most of the time. Makes the sap flow easier. Same with rivers and streams.
Not too sure if that was clear or not (long week, longer day) but I hope it helps none the less. Keep up the good work and hope to see more from you