Hummmm... You ask a comment from me so I guess I'm gonna let it here.

As this wall got into the gallery and got a C+ you already know it's good.
Of course it's always possible to improve a wall but sometimes it's not needed. Anyway you asked so I'm gonna try to be really picky (even more than usual) and give a useful comment.

So here I'm...

First I would say that the overall desaturation of the colors is very nice but a bit sad looking.
The texture on the character gives a strange feeling about the colors also. I would like to see the wall without it just to check how it's like.

You're missing some shading on his right arm (at the bottom near his hand in his pocket) cause if the jacket is on his arm and as the light source comes from the left side (I guess.. Not sure :-s) your jacket should make some shadow on his skin.
Same sort of comment for the sash. You made some nice white parts to show the light on it but you didn't add any darker space where the sash is under an other part of it.

About the light effect on clothing. You could maybe make it a little less strong. I mean... You could try to make a gradient or make it a little more blurry to give a feeling of glow better than a blocky part of white. It's sort of the same for the shading on the coat... When you look at shading on a picture or a photo, you can see that some parts are darker and some other less... Darker parts show a deeper curve and lighter less curved part of the coat. Here all shadow is about the same darkness and don't have any change in each shading.

A little question... If the coat has a dark shading at the bottom, why doesn't the t-shirt? I mean, it's supposed to be lightened the same way no?

The shading under the sash is a bit too big. When you put something on an other object, you're not supposed to see a shadow that huge under it... See what I mean? Looking at your shadow his sash looks like it's 5 cm away from his coat... Kind of strange!

His hearing could have a little shadow too. But that's really a detail. And his hair could also too. In the bottom especially.

The background looks like water color. It's really eye candy but if you ask me, it's not really fitting perfectly with the outlined style of your character. But that's probably my taste! :D I don't have the same taste as others around here. Proof is probably my rates that are really low! :D

Anyway I hope this helps a little... I really like this vector even if the colors are too plain for my taste...

Keep up the great vectoring work! :)