It's very difficult to argue that we haven't overpaid for Rice, but all being well we're going to get him going into his peak years, at his peak years and beyond.
We're now three years on from paying £45m for a 27 year old at his peak. Clrnc is right to say Partey was a monster in La Liga and the CL, but we've seen in each of the last three years, Partey can't handle the demands of the Premier League season. We don't have that worry over Rice.
Essentially, Partey's transfer fee works out at £15m per season. Rice, even if we're only were to get five years from him (and we might reasonably expect more) works out at £20m per season. It's not such a huge difference.