For an uneducated guess, it's right on the money. The KPA chain of command is the most inflexible system imaginable. Their battlefield commanders are expected to execute their orders to the letter, and do nothing without express consent and direction from higher.
The U.S. system is decentralized, with great lattitude and freedom given to lower echelon commanders to get the job done. Even the old Soviet order of battle was somewhat flexible, if overly formulaic. The Korean People's Army, on the other hand, doesn't move without orders, takes no initiative, and exploits no opportunities. Their training exercises are rote, the outcome is known before they start.
While they'd be able to inflict massive damage due to brute strength at the onset of the war, they don't have the flexibility to take advantage of early battlefield successes and press the attack.
The number of 1.2 million troops is not entirely accurate, either. That's just their active duty regular Army. For rear echelon troops, they have the Red Guards militia, a standing active duty militia force of 750,000. Also, there are the Worker-Peasant Red Guards, around 4 million total, which is basically everyone who can shoulder a rifle and throw a grenade. Finally they have the Red Youth Guards, another 1 million or so teenage militia combatants. Many of the militia units have heavy machine guns, ADA, and other types of high end military equipment that makes them more then just armed peasents.