Had the surgery, and yep, what they tell you about how hellacious it is for adults, is absolutely true. I had cancer removed from my scalp and chest when I was younger, and crashed during that surgery with atelectasis and bilateral aspiration pneumonia; and I can honestly say that this is significantly worse pain than that.
Here's what they don't tell you, though. It should be a no-brainer that your surgery will take place in your mouth, right? What is in there that might be in the way? (ding-ding-ding!) You guessed correctly, your tongue! So if it is likely to be in the way, what do they do about it? They clamp it down, of course!
Like I said, they don't tell you that. They also don't tell you that they will clamp it down with so much force that it will cut off circulation to the tip of your tongue making it numb for a long time after your surgery (it's still numb, and I'm on day 6). Nor do they tell you that the clamp is so tight that it can actually cut into your tongue. Or that it will put so much pressure on it that it will spread out to the sides and form open ulcers on both sides where it was ground into your teeth.
I'm back in school today for the first day, and because it's an hour drive each way, I'm sans-painkillers. Trust me, it's as bad as you think it might be, if not worse.