I can't say from personal experience, but my son Christian had his deviated septum repaired at age 10 when he had to have sinus surgery. He was having near-constant sinus infections and passing them back and forth with his dad. CT scans revealed that his sinuses were nearly closed off and his septum had collapsed as a result of a previously broken nose that nobody knew about(Christian falls a lot and is nonverbal, so he has has some other broken bones too--makes me feel like Parent of the Year, let me tell you!)
Anyway, I was nervous about allowing the surgery but we couldn't get this low-grade infection to go away, even after 11 months of antiobiotics. At that point i was more worried about the exposure to the antibiotics than i was about the surgery!
Christian went in for what was supposed to be an outpatient surgery, but he ended up staying overnight.(The went ahead and took the adenoids while they were in there) He has had trouble waking up from anesthesia in the past and it took him awhile to get awake. This did not worry me too much because it had happend before. We had this done in a children's hospital, so the nurses were very knowledgable and comfortable dealing with a developmentally disabled child. Next morning we took him home and he was back to normal very quickly.
We have no idea how much pain there was--Christian is nonverbal and has a high threshold for pain. But he managed with just Tylenol for pain. He wouldn't keep ice packs on so we didn't fight him on that. But there was little to no swelling. We had to do nasal rinses every day to wash away the remaining debris, which he did NOT love. I dont' know if it hurt or if he just didn't like salt water squirted up his nose. But he went along with it. Never had any trouble eating or sleeping.
The best part is this: sinus surgery almost completely cured Christian's sinus infections. In the past 7 years I think has had exactly *two* sinus infections. Christian seemed to have little pain and aggravation afterward. In my opinion, this was one of the best decisions we ever made and has had long term positive effects.
Hope your procedure goes as well as Christian's did.