3.5 seasons and very highly rated by his peers apparently, as well as the players under him at Man City.
Guardiola, Wenger and Pochettino have all mentioned at some point that they believe he will make a high quality Manager.
I guess people would've asked the same questions of Guardiola at Barca and Zidane at Madrid, and that seems to have worked ok.
A gamble for sure, but why not. I'm keen.