"We have just concluded what I believe has been two weeks of successful discussions," UN Syria envoy Geir Pedersen told reporters in Geneva.
"Frankly I believe that it has gone much better than most people would have expected," he said.
His comments came after a first week of intensified talks on amending the war-torn country's constitution ahead of possible elections as part of a UN peace plan.
The talks kicked off last week with a ceremony and plenary session involving 150 delegates -- split evenly between Syria's government, the opposition and Syrian civil society.
But since Monday, a reduced group of 45 delegates have been meeting at the UN's European headquarters with the aim of getting into the nitty gritty of things.
The constitutional review has been touted as a possible step towards ending Syria's conflict, which has killed more than 370,000 people since 2011.
It is a central part of the UN plan defined by Security Council resolution 2254, adopted in December 2015, which also calls for UN-supervised elections.
Pedersen hailed that the talks had taken place in a "very professional" atmosphere.
"They have started to listen to each other very seriously," he said, pointing out that "these are sometimes very painful discussions, and it takes courage to sit and listen to the other side presenting its views on these issues."
"This has indeed been a very good beginning," he said.
Yet the discussions appeared to have remained in the preliminary stage and, with no set deadline, it remains unclear how long the process could take.
The delegates have yet to determine if the committee should simply adjust the existing charter from 2012 or write a new constitution.
Damascus has indicated it is merely willing to tweak the existing constitution, but Ahmed Kuzbari, the meeting co-chair representing the government-backed delegation, told reporters both scenarios were possible.
"We could draft a new constitution as long as it meets all of the objectives of the Syrian state," he said, insisting on respect for Syrian sovereignty.
But he stressed that "we did not come to build a new state," pointing out that Syria "is a state, it has a constitution and a parliament, and a government... We came here to reform the constitution".
Kuzbari insisted that all sides should be able to acknowledge on the need to fight "terrorism".
"This is a fundamental question for us. All parties must agree with that."
Hadi Albahra, the opposition representative co-chairing the meeting, said there was no problem condemning terrorism by internationally-recognised terror groups like the Islamic State or Al Qaeda.
The problem is that "there is a huge gap in the definition of terrorism", he said, pointing out that Damascus has labelled the opposition as a "terrorist group".
He acknowledged that the talks had "not been easy", and that he and Kuzbari had not shaken hands.
But the fact that the delegations met in one room can be seen as a step forward, after years where Pedersen's predecessor Staffan de Mistura shuttled back and forth between delegations in separate rooms.