OK, no flaming, huh?
Ayukat's post indicates that he has not thought this out carefully, and the fact that he has yet to perform his service serves to further emphasise the baselessness of his opinions.
Speaking from the perspective of a person who has spent ten years in an environment where national service does not exist (Australia), I can clearly see what I personally got out of national service. Perhaps my experience in 1 CDO is unusual, or so my friends from other units keep telling me, but nonetheless it is an example of what a national serviceman can take away from his experience.
First and foremost, NS provided me with an environment in which I could develop a work ethic, which was something that I did not experience in school. The tasks that we had to perform had an element of reality to them that academia could never hope to imitate, and that provided a sense of purpose for developing said work ethic. I did more and did it more thoroughly than my classmates at university. At work after graduation, this work ethic has also served me very well.
Second, having performed some rather challenging tasks in the course of duty, I walked out of the army a sense of confidence that I could deal with any situation. While my university classmates were running around like headless chickens at crunch time, I was already accustomed to making sure I stayed calm so that I could do the job right. Again, at work, this was a great help in giving my employers and clients a strong sense of confidence in my abilities.
As a spin-off of the confidence I developed, I also learned to stop running around trying to prove something, only to find that I didn't know what I was trying to prove and who I was trying to prove it to. While many of my classmates were wasting a whole lot of time and energy with grandiose but effectively useless projects, I made every move count. When I was supervising Honours students completing their theses, the first thing I would teach them was the concept of mission requirement, so that they didn't waste the ten short months they had to produce their theses. Of all of my students, only one student went as low as a lower second-class - she was too set in her ways to grasp the concept. As for the rest, they have all gone on to employ the mission requirement concept in everything they have done subsequently. Applying the concept to my own thesis, I currently hold the department record for producing a 30,000-word thesis: 8 months out of the 3-year allocation.
In the course of teaching, I also adapted the military method of instruction and communication to my needs - this helped me to ensure that I got the message through clearly to my students, and in later years, to my clients and colleagues.
When I was working as a human resources consultant, my military background helped a lot - the field of human resources grew out of the military during WW1, and the industry's enchantment with the military remains very strong today. Of course, "1st Battalion, Singapore Armed Forces Commandos" makes one hell of a brand name!

At the end of the day, the skills and working principles I picked up during NS, with subsequent development and enhancement, have been a great help in tucking the competition away.
This has all come from one very simple decision: "I'm stuck here for the next two and a half years, like it or not. I may as well get as much as I can out of it".