Neymar became the world's most expensive footballer after leaving the Catalan giants for PSG in a €222m move at the start of the campaign.
The Brazil international has enjoyed a blistering start to life in the French capital, scoring 20 goals and bagging 14 assists in 20 games in all competitions so far.
However, former Barcelona star Ronaldo believes the move was a step down in terms of his footballing development.
"Sportingly, the decision is a step back," Ronaldo told ex-Brazil international Zico in an interview via YouTube.
"But there are challenges that everyone seeks.
"I played in Barcelona at the time and went to Inter when the Italian championship was much more competitive."