The main aim of signing Ronaldo for Juventus was clearly to win the Champions league, which they didn’t achieve. I see this as the main reason why people claim Ronaldo wasn’t a good signing for Juventus. As well as him being one of the main reasons for Juventus’ economic issues.
If we are talking about sports result absolutely not, Juventus was doing quite well in champions league before him and they recruited him to finally win one and stop losing in final.
They literally couldn’t get past round of 8 with him and they even couldn’t win the Série A in his last season (I’m not saying that all of this is his fault but this was the main purpose of his move to Juve).
But if we are talking about marketing etc… it was a huge success, he made a lot of people follow Juve and buy his shirts