Ronaldo is the main reason I'm watching SPL games and surf out details regarding the league. Because to Ronaldo, the Saudi Pro League has developed to become one of the most recognizable competitions in Asia football, and most European football fans now watch and stream Saudi Pro League games. Al Nassr are privileged to have him on their side; he's always one courageous guy capable of producing miraculous events in games, I mean comebacks. The move of Cristiano Ronaldo to Saudi Arabian football has transformed the league's quality in terms of severe competition, and there are good means of competitive race.
It is not only you, most people are interested to watch SPL (Saudi Pro League) because of Ronaldo. However, there are already many other top players in SPL, too. Some people may watch the SPL because of other players as well (such as Benzema, Mane, Neymar, etc). However, we must admit that Ronaldo makes everyone in the world knows SPL, it is quite popular now. I'm sure there are few people only who know SPL and Saudi clubs before Ronaldo moves to SPL.
Al Nassr gets a big advantage by signing Ronaldo. This club becomes more competitive although they still couldn't win SPL trophy with Ronaldo. However, there is a significant increase in the popularity of Al Nassr, and there is a big improvement in the merchandise sales, too. Those are just 2 examples of the advantages besides the increase of squad quality.
As the whole, I can agree that having Ronaldo, SPL becomes more competitive. Moreover, other big teams in SPL follow what Al Nassr did. They also signed many top European players.