They can feel everything. I've had some people tell me they put themselves almost into a dream state when they have sex. They like to watch. Also, there's a certain amount of just wanting to function as normally as possible. To realize that they can sexually function and sexually satisfy their partner is satisfying and pleasurable when it occurs.
Sex is still mostly between the ears.
In most cases, the testicles continue making sperm after spinal cord injury, but ejaculation is impeded. So the challenge for men with SCI who want to become fathers is to get the sperm out of their bodies so it can be used for insemination. One of these is to place a vibrator against the head of the penis to stimulate a reflex ejaculation. This method has been in use for about 13 years, and works best on men with injuries above L2, in whom the necessary reflexes are most likely to be intact. The second method, which has been in use for 6 or 7 years, is to stimulate the prostate gland, the seminal vesicles, and the vas deferens with an electric probe inserted in the rectum.