With his high ratings in the opinion polls Nikolic is getting a lot of publicity in the Western press. A review starting with Nikolic's assertion that he differs from Milosevic.
Lets start with a symbolic similarity: both men have some association with death. Nikolic is "the undertaker" and Milosevic had suicidal parents.
Nikolic blames Milosevic for not completing the actions in Bosnia and Croatia. He says that he would have gone "all the way". To a certain extent he is right: openly sending troops and claiming that the right to do so would have been a better strategy than what Milosevic did and might have prevented the steady erosion of the Serb position in Croatia after the 1992 ceasefire. It also would have prevented him from being dependent on the irresponsible leaders of the RSK and the RS. But this would have required a smart legal strategy that would have denounced the recommendations of the Badinter Commission and I doubt Nikolic could have accomplished that.
Another thing that Nikolic has in common with Milosevic is disregard for public relations in the West. Milosevic lost much support because of the cruelties committed by Serb troops. But there were also missed chances: Serb refugees from Croatia and inside Bosnia were virtually invisible in the Western media. Nikolic seems not much different when he says that Mladic and Karadzic will not be extradited. He has some point when he says that that would mean that he did the same as the present government with the only difference that he is honest about it. But he will need to use stronger arguments like the death of Milosevic to convince the Western public of that strategy.
One of the weak points of Milosevic was that he seemed to feel inferior towards the Western negotators. That led to servile behaviour to "please" them. But sometimes he had to come back on those gestures or he couldn't deliver: that give him an unreliable image. And at other times he gave more than he should have. In a recent IHT article Nikolic was described by anonymous Western diplomats as "more pragmatic" than Kostunica who was seen as a "19th-century, anti-Western, romantic nationalist". That may indicate a similar "pleasing" leaning in Nikolic.
Another weak point of Milosevic was his lack of strategic thinking. Milosevic reacted to situationa and seemed not to have a long term strategy. Obviously he didn't foresee the shift of power that ended with Operation Storm until it was too late. By demanding less in the beginning he might have achieved more. If I look at Nikolic I can't see any grand strategy either.
Nikolic chooses for at least two policies that are in conflict with Western wishes (Kosovo and Mladic/Karadzic). This is not impossible but to pull this off he will need both strong public relations to explain the Western public what he is doing and a consistent strategy. Milosevic was in a similar position and he failed miserably. I see no indications that Nikolic will do better.