I had the same surgery but it was many, many years ago.
It was done because I had an open bite. Before the main operation, I had my wisdom teeth removed and some other teeth. If I remember correctly, the day before the operation they fitted these special braces that would be used to wire up my teeth and jaw during the operation.
During the operation they removed bone in two places at each side of my jaw. I have a small faint scar just below each ear which nobody notices unless I point it out to them. I was wired up and sent to intensive care after the operation for the night as a precaution. I had a few issues and so was there for a few more days.
My surgeon had said before the operation that it would take me a few years to adjust to the new shape of my face. He'll, I had lived with the old shape for so many years before.
It did take a while to adjust as my face shape was quite different. Good news was that before the operation I had a gap between my upper front teeth but after being wired up it went. And of course my bite was fixed and I could bite a biscuit or an apple using my front teeth which I couldn't do before. Also if I hadn't had it done and my back teeth which was the only point where the top teeth and bottom ones met would have worn down a lot ant then how could I chew things?
I hope this information helps. If you want to know anything just ask.
So on the whole I was glad it was done. Hopefully you will feel the same way too after your operation.