Besides getting a deer, it's the quiet of sitting alone in the woods. I have always felt that sitting in a tree for hours is kind of like having a zen moment (or hours) and I love it. I don't think I have appreciated it as much as I probably will this year.
As I write this, my three month old is having a total melt down over nothing (side note, I will eventually put his photo here http://www.reasonsmysoniscrying.com/ for others to smile about. It's a GREAT blog). And as much as I love spending time with my family and cuddling with my son, I have not had me time for a while. I look forward to being alone in that tree just listening to the birds, squirrels and passing traffic.
An added benefit of hunting season - good mental health!