First of all, if you didn't ask for scrutiny, I wouldn't have noticed anything 'missing'. Taking it at surface value, I think it's a very beautiful scene. But if I must go through and look for flaws, I would say the first thing I noticed is that there is a lack of imperfection in the architecture. More specifically, in the edges. They stand out to me as being very straight, which contributes to the overall feeling of excessive symetry or perfection. I see that you offset this phenomenon a bit with some of the mossy-looking textures at the bottoms of the pillars, but I would expect to see some cracks in the walls, perhaps starting at the top of an arch and traveling up about a foot. Only one or two, maybe three cracks in appropriate places - it should look weathered, but not ancient. And I would roughen-up the edges of the architecture some more, perhaps with some bump maps. I like how the shutters aren't all doing the same things (some are shut, some open, some in-between), but maybe some of them could have some signs of wear like some missing slats, some with excessive fading of the paint (perhaps because they get exposed to the sun longer because of where they are), or some with a different paint color because the tenants didn't like the stock color. And maybe there are some props you could add in to make it look 'lived in'. Maybe some empty bottles where someone had been lounging earlier or some old shoes on the dock. Any little artifacts left behind by the people who live/work there would probably really help the viewer experience your scene and imagine themselves in it. The more lived-in it looks, the more it goes from a 'scene' that they can see, to a 'habitat' that they can relate to. But as with anything you don't want to over-do it.

Finally, there seems to be some disagreement between the direction of sun light for the background buildings and the direction of sun light for the foreground.

But all in all, I think it's very good! Hope this helps.