I am not a wine expert, so I couldn't really say. I have had it served both ways, and it will always be my favourite wine whether it is chilled, or at room temperature. It may have a sharper taste if it is slightly chilled, but I have no preference.
Paradoxically, as one who hates cold fluids, I think Moscato needs to be chilled. I actually find it can be a bit "chokey* when it is room temperature. It seems to travel down better when it is cold. *cough choke gag*