Actually, the situation is quiet in almost all of the country. But still, this is not exempt of exceptions#:

Human rights violations by security forces and police in the south
Amnesty International documented human rights violations by security forces and by members of the Sudan People’s Liberation Army (SPLA) during the April 2010 elections. In the south, as well as the north, journalists were arbitrarily arrested and harassed for reporting electoral violations. Voters and members of the opposition were also harassed and intimidated in some parts of the south.
Although the preparations for the referendum have been relatively peaceful, it is essential that authorities issue clear instructions to all members of the police and armed forces to respect and protect the human rights of all citizens, and make sure that any perpetrators of human rights violations are held accountable.
Violations by members of the SPLA in various parts of south Sudan, including attacks on the local population, have been reported in recent years. The threat of outbreaks of violence may restrict movement in some areas. Amnesty International calls on all law enforcement agencies including members of the SPLA to allow the freedom of movement of all citizens
.
http://www.amnesty.name/fr/library/i...54/002/2011/en

Six killed in clashes between SPLA and rebel militia ahead of referendum

At least six people have been killed and 26 taken hostage in clashes over the weekend in Unity state between rebel militias and southern Sudan’s army – the SPLA – as the military give conflicting details on the attack, which comes days ahead of a referendum on the region’s independence.
SPLA spokesperson Philip Aguer, said the southern Sudan army ambushed militia loyal to Galwak Gai. He also claimed in statements to Reuters they were sent by Khartoum to disrupt the south’s referendum.
“From our side, I am told no single soldier has been killed. There are also no reports of injuries on our side from the ground but I am told six on the side of the side of the attackers have been killed.”
“Two (of Gai’s militia) were killed yesterday on Friday and additional four others were killed today on Saturday and our forces are following them. They are conducting hot pursuit. They will not give them room to sabotage this coming referendum so that our people exercise their rights to vote in a free environment. They will make sure that they are outside southern territory today so that [the] upcoming vote is conducted in an in security free environment. They will make them run and bring them under control,” Aguer said.
http://www.sudantribune.com/Six-kill...een-SPLA,37531

Clashes ahead of Sudan referendum

There was also fighting reported in the disputed border region of Abyei over the weekend, leading to as many as 9 deaths, said Charles Abyei, the areas speaker of the assembly. While details remain unclear, the fighting was reportedly between members of the Ngok Dinka and Misseriya tribes.
http://www.prokerala.com/news/articles/a193697.html

But the voting period is not the critical one#! The immediate post voting, January 16 until results proclamation, will be critical one as the Southerners will realized they just voted to have the right to become independent and are not independent. And then after July when they will realize that they have no enemy to unify them and that SPLM is not capable to deliver what it promised them.