I had one just last Monday and have a post on it called "dread, Dread, DREAD".
I had to drink the EZ Prep. It is not so bad. Only one 12 oz glass and it worked. Be prepared to spend a lot of time in the bathroom. I had a tv table with laptop, books, etc set up and ready. I was afraid I would be hungry, but you are so focused, you don't really think about it.
The procedure itself was a BREEZE. Nothing to it.
In 52 years, I've never been put to sleep. I did have a problem with nausea and throwing up after my procedure that was caused by the anesthetic. If you don't have problems being put to sleep, you should be fine.
"Chisel praise in stone; write criticism in sand."