Inter fans absolutely love him and are mad that they can't afford keeping him. He was fantastic for them.
40m seems like much, but people also complained about paying 46m for Douglas Costa last year. Prices have changed, time to get used to it. One good season and you're worth >40m, that's the new reality.
Having a highly talented 24 year old fullback on a 5 year contract, who has proven himself in Serie A, is a much better proposition than signing Darmian, who's room to improve is limited.
I'm for it.