He's quite good but I get the impression Newcastle despite their money aren't the first choice for top players or top talents, so they will end up signing players like this who are good, and who top clubs have looked at, but decided against committing to a transfer. Newcastle will probably end up overpaying as clubs will want to exploit them for all they can. Would make sense for why the signing is quite late in the window, player holds out for other options before deciding to take up Newcastle's offer. I expect they will do one or two more similar deals before the window shuts.
It could work both ways, they may snag some top players before other big clubs are in for the player, but they may overpay for some players who aren't good enough enough to justify that price.