You shouldn't have severe pain with this surgery. Most men regain bladder control a few weeks to several months after the surgery. The main advantage of surgery is that it offers the most certain treatment. That is, if all of the cancer is removed during surgery, you are probably cured. Also, the surgery provides your doctor with accurate information about how advanced your cancer is, since the lymph nodes are taken out along with the tumor.
Surgery does have risks and complications.
You could lose a lot of blood during this surgery. Before the surgery, you might want to save about 2 units of your own blood in case you need a transfusion. Fortunately, a very low percentage of men have severe incontinence after radical prostatectomy. The chance of impotence decreases if the surgeon is able to avoid cutting the nerves. This may not be possible if the tumor is large.