wow, what a cute face! I really like the expression, though I think it lacks some technicals. the lighting is really just flat, meaning there isn't much shadows created by your light source. I'm assuming you used on camera flash here and the catch lights in the baby's eyes are in the dead cener of the eye making it both flat and a little weird to look at.
again I love the expression though, and with kids that is more then half the battle. mabey use some light from a window next time and I think you will be in business.