I left my first colonoscopy until I had colon cancer -- too late
I spent 7 days in hospital and lost a third of my colon, and I consider myself one of the lucky ones ~ other family members haven't been so lucky.
Compared to the surgery, a colonoscopy is a breeze. Those of us who have been through the prostate cancer mill (DRE, biopsy) will be in familiar territory. As Steve and Garth said, the hard part is the preparation.
Colo-rectal cancer is very curable if caught early, but deadly if not. And as it is a very common cancer in men and women, we should seriously consider checks from around age 50.