A pretty good summary report of the Abyei decision and outcome is here.
The decison, as noted in earlier posts solidly defines the territory of the Ngok Dinka and (in a bit of over simplification on my part) defines much of the disputed area of Abyei into Southern Sudan.
The two most productive oilfields (Heglig, Bamboo) in the area were not included in the definition of Abyei. That means that unless the north-south boundary commission and the oil commission don't find a solution internally, there will be another arbitration process (yet to be defined).
So, is this a good or bad development? I think neither. It is a necessary process that will be undertaken no matter what happens in Sudan's future.