Since Craig made a big deal of this in his debate with Sam Harris, here is Wes Morriston's critique of it. Link. Here's a quote:
Either God has good reasons for his commands or he does not. If he does, then those reasons (and not God's commands) are the ultimate ground of moral obligation. If he does not have good reasons, then his commands are completely arbitrary and may be disregarded. Either way, the divine command theory is false.