How do you critique a spontaneus child portrait? It's impossible to be fair.
The hard thing for us parents when we take pictures of our kids is that we know what their facial expressions means. You can probably read alot more out of the picture then any outsiders can. I can see that it is a cute kid in bed. Technically it's a great picture, good contrast and a nice conversion. The light is not harsh and hits him gently in the face. Excellent capture.
The image itself does as I already said dont tell me much about what he thinks about being there and what he is doing there. If you did not tell me, I would assume that he was a bit upset and did not at all want to go to bed, rather then has already gone up.
Don't take this as bad criticism, it's not. I think it's a great picture. And I do myself have the very same problem with my daughter. I got a ton of fun pictures, but they only speak to me, my wife and other family members that knows her well. I am trying to learn how to "show" the viewer whats going on by using the enviroment around and different "props". But it is hard, and I assume thats why we have few successful children photographers.