The bad news for Ahl Hilal is about Neymar and it seems he is still injured and there is a chance for this player to be absent for a few days in Al Hilal which can have a negative effect on this team however after Neymar join Al Hilal the fans were happy to see this superstar player in their teams and there was a positive atmosphere in the teams, also I think Neymar can have a player like Aleksandar Mitrović as forwards for Al Hilal which can make this team to have very strong forward for this season.
In my personal opinion, even though Neymar is currently injured and cannot immediately make his first debut with Al Hilal, this will not reduce Al Hilal's performance. That's all because there are still other players who can be relied on, such as Ruben Neves, Aleksandar Mitrovic, and Milincovic. So even though Neymar hasn't been able to make his first debut in the near future, in my opinion this will not reduce the performance of al hilal.
It is not worse news from Neymar for Al Hilal because he will be older and more sensitive with injuries. He will be like Bale after his 30s and Neymar is very unprofessional with his lifestyle which can make his body more sensitive with injuries.
The transfer to Saudi Arabia where is abundant of entertainment services will give Neymar more chances to enjoy his life. In return he will less focus on football and more injuries, less appearances, worse performance will come with time. Ah Hilal did not sign a long contract with Neymar and perhaps they will wait the first contract expires before considering to sign a new one with Neymar.
Yes, you are right, that when he was at PSG, Neymar really couldn't take care of and didn't manage his lifestyle properly. It is often reported that Neymar is skipping practice and what I know from several news sites, that Neymar is often drunk. Which resulted in decreased performance when playing or during practice. So looking at the habits that Neymar did at PSG,
the possibility that Neymar will repeat his habit at al hilal, is still very large. Even though in Saudi Arabia alcohol is still strictly prohibited by the government, it does not rule out the possibility that in that country alcohol is still being sold clandestinely. But hopefully, Neymar can maintain his lifestyle better, so that his performance will be even better, so that he can provide games and shows that are very entertaining.