Depends on how brainwashed he is.
He can either be a great tyrant, or he can hand the power to his people through a representative government. The latter would be King-like, and probably the only honorable act his particular heritage could perform at this point.
50/50

In fact I would bet he already has such an affectionate nickname already assigned to him and drilled into the minds of the people. Jong-un won't have the same amount of time given to his public programming phase, or, the period where he is drilled into the consciousnesses of the Korean people with fables of his greatness and things like that. Jong-il was chosen by his father in 1979 and was almost immediately dubbed "Dear Leader" to compliment his fathers "Great Leader" status which Kim will never attain...remember...Kim Il-sung is STILL the president of North Korea even 16 years after his death. So, Jong-un can never be either Great Leader or Dear Leader as those two positions will be held for "ever" by the current figures...but he assuredly already has some affectionate title already being pushed to the hapless North Koreans like so many bowls of "nutritious steam" for lunch.

The problem that they will run in to the most is Jong-un's age. He's only 27. Selling a 27 year old boy to an elder worshiping North Korea will be a hard sell. That's why Jong-il got 15 years of being indoctrinated into the public mind before he took power following his fathers death in 1994. Jong-il will be dead before the end of the year if he isn't already. Cheng Sung-taek, the Vice Regent will continue to administer daily affairs of North Korea until Jong-un has "gained more experience" (and lies of miracles attributed to him and glorifying his greatness get more widely disseminated).

Everything I've read so far about Kim Jong Un points to him being a real chip off the old block, doesn't look like things will be getting better for the people of NK for a while yet