Without these nerves, the bladder neck does not close during ejaculation, and your sperm end up in the bladder instead of where you would expect them to go. The good surgeons are successful almost all of the time, but the regular surgeons with little experience with the operation are not particularly successful. Some men recover the ability to ejaculate without treatment, while others may be helped by medication in an effort to regain their fertility. Most, however, will simply have dry ejaculations. As I understand it, it essentially feels the same, but without the wet spot.
Some men claim that it does feel different.
If you end up having radiation therapy it should not change your ability to have sex whatsoever. Radiation therapy can, however, interfere with sperm production. Usually the effect is temporary, and most patients regain their fertility within a matter of months. As for chemotherapy and its effects, men who receive chemotherapy for testicular cancer continue to function sexually, although some anticancer drugs interfere with sperm production. Although this effect is temporary for most patients, some may become permanently sterile.