I'm starting to look closer at fortifications, since they seem to feature on many maps but seldom gets commented.
Your walls seem good, they surround the whole city and have a castle inside.
A couple of things thou
-Would you rely on the hill only for defence north of old town and east of the harbour? I think the hill should have walls. It could be that parts of the old city walls was destroyed or dismantled on the hillside, so it's not essential.
-The southern road lacks a gatehouse and will be very hard to defend and since it's a long stretch of wall with a hole in it, it will be very weak.
-Same with the entrance to the castle, if the entrance is where i think it is
A gate is a hole in the wall and that makes it the weakest point. To make it tougher the builders almost always put a gatehouse over it, a thick, hard tower. The gatehouse had lots of nasty surprises for anyone trying to break down the gate.
The only gates that's frequently not defended like this are the sally gates, small gates in the back or an area that has other defences. Those gates were used for sallying forces that tried to drive off the attackers and were kept unused and often secret.
On another note, everyone has seen those big corner bastions on medieval castles. The purpose of those oversized or hanging towers was so the defenders could get an angle on the walls to either side. Later the star fortress was invented where the towers were lower but the anle of the walls was made to minimize the uncovered wall sections.