One of the problems is that of phantom pain which is pain you feel on missing limbs. So, one of the dilemmas would be, you cut off your leg, you put on a bionic leg, but then you begin feel pain in that missing leg. People lose limbs in war. When they come back, they continue to feel pain at times in their missing limbs. When you attach things to your body, your body can consider it (them) as invaders, germs, viruses, cancer, etc, and attempt to reject and destroy it. There can be side-effects to the extent technology is not perfect. So, if you can make a PERFECT PERFECT PERFECT thing for your body to become a cyborg, then you could hypothetically benefit from it. Another problem is that even if it helps you, it may not help another person who may be encouraged to do what you do. Some people may then do it and die. Another major issue is that cyborgs could be hacked remotely if there are no manual override mechanisms. Remote access would be a problem.