I don’t know what else can be added to the scene. Maybe some rocks in the water, but other than that?
Feedback needed in any case 
Hey! Very nice scene! What about a pier with a small boat and stairways to the cathedral?
the cliffs look dull and too narrow… more rocks in the water would be nice…
It looks good, but it feels like the picture could be more interesting from a different perspective. Maybe slightly look up towards the cathedral, or looking down from above it. Its not clear if the focus is the cathedral, or simply the water between the cliffs. To me at least.
The cliffs also look a bit too cube-ish.
Otherwise, good work!