Pros:
1. Prevents prostate & testicular cancer.
2. Will not stimulate aggression (most of the time) when a female dog is in heat.
3. In most cases doesn't drive the dog to wander around, keeps them home, because he couldn't care less if a dog down the street is in heat.
4. Usually helps promote peace, not as much drive to asert their dominance on other dogs or people.
4. Most neutered dogs will not mark everything constantly, esp. if you neuter them before they start marking.
Cons:
1. The anesthesia has some risks, including death, but if your dog is healthy the odds are in his favor.
2. The incision site may become infected, pursed or reopen, but if you keep an eye on it, you can catch it before it becomes a problem.
3. Some people say it makes their dogs fat, but with proper nutrition and exercise that will prevent that.
I think its a really good idea, you will never have to worry about dealing with your neighbor coming over talking about an unwanted litter because your dog jumped the fence and hooked up.
You'll not have to worry about your dog attacking other dogs in their own yard and people because of his frustration about the dog in heat he can't get to.