The biggest things that most people face when coming off is just frusteration at not being able to make gains. It can mess with your head if you let it. The combination of that with the changing of your hormones is what I believe leads people into depression. It is also what will get people to jump right back onto cycle.
Some people experience impotence. If you are doing a correct pct, that shouldn't be too much of a problem. Also, if I experience any of the sides, such as acne, it is usually right after I come off.
"I firmly believe that any man's finest hour, the greatest fulfillment of all that he holds dear, is that moment when he has worked his heart out in a good cause and lies exhausted on the field of battle -- victorious" Vince Lombardi