Well, My son and us finished the game he was DMing tonight. Overall, I'd say he handled it pretty well.
He wasn't as familiar with the game as he could/should have been. He was a bit to lenient, in my opinion in the monster encounters as well. Then again, he was just excited to pit the monsters against us without having TPK on his hands.
He gave away way too much treasure in terms of magical items.
In context though, it was a fun game and he seemed happy that he got through it all without asking me to take over (his words). Basically, he dealt with issues all first time DMs's deal with.
He wants to DM again, that's a good sign. I know I and my daughter both said we enjoyed the game and would play with him as DM again. Which made him feel good.
Now, my daughter is looking even more forward to her turn as DM next week. We'll see how it goes.