I just had mine out 2.5 weeks ago, and according to my surgeon the recovery is a breeze for the little tykes. It's horrendous (I'll second that!!!) for adults. I'm still sore from it.
Aside from the anxiety about medical procedures that kids sometimes experience, he should be feeling good after a couple of days.
DD1 just had her tonsils and adnoids removed last Oct and she did just fine. It was a little rough the 1st couple days, but they really do bounce back so quickly.
A word of advice... DON'T fall behind on the pain relievers. Riley doc said to alternate Motrin and Tylenol every 4 hours for the 1st few days whether we thought she needed it or not. I didn't wake her up during the night the 1st night and she woke up crying.