Looks great. Very nice coastlines. A few thoughts:
The landforms are very natural looking. The south-west peninsula of the north-west island reminds me a lot of the Avalon Peninsular in Nova Scotia, what with the tiny isthmus connecting it to the rest of the island and all.
The island groups in the southeast seem to run along three straight lines. It looks a bit odd, since I expect islands groups to form more of an arch.
The map seems to be neatly divided into four quadrants. That introduces a slight level of artificiality to the map design that subtly jars with the natural looking coasts. It just looks a bit too symmetrical and planned. Moving the southern of the two north-eastern islands west-south-west a bit and introducing some arch to the southeastern archipeligos would go a long way toward making the land placement look a bit more natural to my eye.
All in all though, a great map. I really like the color you used for your ocean. What is it?