The tournament, designed in part to remove meaningless friendlies, was initially met with scepticism and questions about the need for another tournament and its complexity.
Ahead of the last set of pool matches on Tuesday, England, the Netherlands, Portugal and Switzerland have qualified for the finals in June, while Germany have been relegated from the top tier.
"The Nations League was and is even more successful than we thought. We always had complaints from the big football countries - 'We play with small countries', 'We don't play amongst each other' - and we always had complaints from small ones - 'We never win'," UEFA President Aleksander Ceferin told a news conference in Brussels.
The tournament also offers spots for the Euro 2020 championships, with knock-out matches between teams in every group from top group A through to bottom-tier D.
"It's very interesting, and it's the road to Europe, which is also great for the D group to qualify to Europe. It was almost impossible before. All the numbers are fantastic," Ceferin said.
The UEFA president said promotion and relegation from groups made the tournament interesting, even if he had not been happy with his own country, Slovenia, dropping to the bottom tier.
Andrea Agnelli, the chairman of Juventus, told the same news conference that the pool stages of the Nations League had been a success and believed players had enjoyed it.
Agnelli, who is also chairman of the European Club Association (ECA), which represents more than 200 European clubs, denied that plans for a European Super League were back on the agenda, as Germany's Der Spiegel has reported.
"The future has to be written. What is ruled out, it's the Super League," Agnelli said.
"What I can rule out from a Juventus perspective, from an ECA perspective, it's no talks of a Super League have been carried out since 2015," he continued.
He said that he and Ceferin were instead concentrating their thoughts on what might be introduced after 2024, such as greater alignment of calendars, release periods of players and mandatory rest periods for players.
(Reporting by Philip Blenkinsop; Editing by Hugh Lawson)
