It is a great deal based on the talent of the player alone.
Is it a high price for someone on the last year of their contract? That is all relative to who else is available in terms of the position, age, skill level, and remaining years on the contract.
Given all that, I don't feel that they overpaid. However, this was not a bargain by any stretch. Getting him for 10 million is a genius move. This was not. But if they were able to convince him to come here instead of Man City, then more power to the management and the club