They have arguably signed the best player in the age range of 22-28. PSG have always been okayish but with this signing everything changes. Add in sanchez and you have a crazy ass team definitely in contention for the CL.
If neymar isn't an impact player for 222 million, I have no idea who is.
They were an "okayish" team before and with Neymar they're not much better. Like I said, his teammates at Barca were much better than his teammates at PSG will be, and we also had a better manager. If he wasn't enough to propel us into European dominance, I see no way he'll do it for PSG.
As far as Alexis is concerned, he'll probably fizzle out at PSG. We knew from watching him in his time here that he can only truly shine if he's the one allowed to be the top man, a role that's obviously going to go to Neymar. Funnily enough, Neymar signing with us was one of the main reasons Alexis left.