The different degrees of smoothness/ jagginess that Viking recommends have terrain implications. Sharp, young mountains you figure 'continue out to sea', with their ridges and peaks becoming peninsulas and islands. When you see a smoother coast you'd generally assume flatter / gentler terrain adjacent. Some of the fractal world generators allow only one fractal degree for the whole globe, and based on Earth :-) that feels unrealistic. Clumps and strings of mountains alternate with plains and steppes and swamps. Your shapes are delightfully intricate, they could just use some beaches - which can have a different kind of intricacy. Look at the US Atlantic and Gulf coasts: barrier islands, capes of sand spits, river inlets, deltas -- and a few jaggy areas that aren't mountainous so much as drowned (the DelMarVa peninsula, and Chesapeake Bay).

A simple way to imply some of the high-latitude distortion Hai-Etlik mentions is to draw like you have, then progressively smoosh the land masses north-south, as you get further from the equator.