Just like with other screenings like mammograms, they are not without risks that's for sure. I wouldn't do it unless I read through this and other sources about the dangers, side effects, etc...
Each year over 14 million healthy Americans are getting screened for colon cancer. Of these, according to the report “Complications of Colonoscopy in an Integrated Health Care Delivery System” by the Annals of Internal Medicine, an estimated 70,000 (0.5%) are killed or injured by colonoscopy-related complications. This figure is higher than the total number of annual deaths from colon cancer itself, 22% higher.