ED depends on a lot of defferent factors. the skill of the surgeon in seperating the nerves from the prostate, your age, if you had ED issues prior to surgery, your overall health, and probably much more. My personal opinion , I think one of the biggest factors is the skill of the surgeon.
I was very lucky and I have had no major ED issues. I was getting rock solid erections the day my catheter was removed and without drugs. The one thing that was very different after my surgery to prior to my surgery was the fact that prior to my surgery, just a simple mental visualization of sex or looking at an attractive woman was enough to give me an erection. Now, after surgery, I can think about sex and look at naked women 24/7 and I feel nothing down there, not even a tingle. The only way I can now get and maintain an erection is with constant manual stimulation. As long as there is stimulation I can maintain an erection for hours if need be, but the second that stimulation stops, so does the erection.
The other thing that is very hard for me to get use to is orgasms. I happen to be one of the unlucky guys that ejeculate urine. I am normally 100% dry, but the second I start getting sexually aroused, I can start to feel my splinkter muscel relax and I will start dripping like a faucet. Even if I empty my bladder before sex, I will still drip a little. What is worse is that I ejeculate urine with such force, I can hit the ceiling. I ejeculate urine with more force now without my prostate then I ejeculated seman when I had my prostate.
My uro told me there is nothing you can do about it and I just have to learn to live with it. He also said that urine is steril so if you ejeculate some in your partner, not to worry because it will not harm her. Just try telling that to a woman! I asked the surgeon, if I am going to ejeculate urine, at least is there a pill I can take to color it white? No such luck. He did tell me to drink a lot of water prior to sex because that will at least dilute the urine and reduce odors. I guess every little suggestion helps. Some people here suggested using a condom, but with I condom, I loose my feeling of stimulation and I loose my erection.
Overall, I will take these small problems any day to the alternative of having cancer.