I just can't think that the argument on letting him cry is valid. Parents have been doing this for years and still have good loving relationships with their children.
Anyway, I personally felt that I was doing my daughter a better service by letting hee learn to put herself to sleep. Otherwise if she wakes up in the middle of the night, she would need me to rock her, nurser her..whatever. I started letting her cry around 12 weeks of age and would set my oven timer for ten minutes. If she went over that, or started to get louder, I would go get her. Most often, she was out within five minutes.
I have a video monitor and would notice her wake up sometimes around 8 pm (she goes to bed at 6:30)..she'll wiggle, make a few sounds, suck her hand a bit and fall right back asleep.
I found the book Healty Sleep, Happy Child by Dr. Weisbbluth very helpful. It really focuses on a routine and a set bedtime.
Keep in mind, it can be harder for a child to go to sleep when he/she is overtired. They can usually go out quicker if you catch them before they're exhausted.
Ultimately, do what works for you and what works for your son. If rocking works and you like to do it..they're only young once so enjoy it and forget what other say. I don't think either way is right or wrong. For me, I just didnt' want to get up and rock her all the time..is that bad? ! ;) hehe