I wouldn't expect their missiles to do very well, considering they're currently cut off from the entire world, essentially. Only China maintains ties with them, and it's a rather lukewarm relationship.
Well, I think the media is going a good job about lambasting North Korea for the failure and then speculating about an irrational response to the "epic" failure. They are a joke of a country and Gov't. but they are also off their rocker nuts. If they follow this failure up with testing a nuke - have mercy on us all.
The DPRK has nuclear weapons, and if they did decide to use one, it'd be on the US garrison in Japan because 1) Koreans (both north and south) hate the Japs, 2) they wouldn't hit South Korea due to familial ties etc., and 3) they would strike a huge blow against the United States, wiping out ~30,000 US Marines, not to mention destroying a major airbase.
This sort of scenario is highly unlikely, though. Unfortunately, because of the way the DPRK is run, re-unification with the south is highly unlikely, barring a massive revolution, a sort of "Asian spring" (which China would never allow, for the record.)
It makes sense since it was the Soviet Side of a Cold War proxy war.
Here is an intro I wrote a while back to an essay about "Why North Korea is the way it is." (Both sections are a bit lengthy but mine provides some necessary historical context on the various outside factions ruling the Korean Peninsula and the linked article does an excellent job putting the DPRK into its current context... so if you're interested, please read, if not, sorry for the long post)
Below I’ve outlined a brief summation of 20th century politics in the Korean Peninsula prior to the period covered in the article to make for a more holistic portrait...
In 1905 the Taft Administration gave imperialist Japan the go-ahead to force the Korean Empire’s leadership to hand over power. The opinion of the U.S. government at the time was that Japan's subjugation of the Korean people would "…contribute to permanent peace in the Far East." Following three-and-a-half tumultuous decades, World War II marked the end of Japan's control over Korea’s international affairs.
The victorious United States and Soviet Union claimed a trusteeship over the Korean Peninsula. Despite the Koreans clear stance against a division, the two powers coercively demarcated North and South Korea, dividing them at the 38th parallel. The Soviet Union allowed the people to organize themselves into independent committee’s and slowly manipulated these committees into a provincial, centralized communist government. The interim government was headed by Kim Il-sung, who would become the first President of the Democratic People’s Republic of Korea.
In the South MacArthur’s delegate, Lieutenant General John Hodge was charged with overseeing the establishment of the new governing body. The southern Korean people organized themselves into The Provincial Government of the Republic of Korea, however, when the group sent a delegation to meet with Lieutenant General Hodge, he refused to speak with them or recognize the provincial government in any manner. Instead, Hodge selected a staunch anti-communist expatriate named Syngman Rhee to head the interim government. Rhee had lived and studied in the U.S. as an exile from Korea and as interim leader worked to eliminate left-wing communist insurrection within South Korea. Rhee would eventually become the first president of the Republic of Korea.
These two countries were soon to become the battleground for the opposing ideologies of the Cold War…