Everyone should be cautious. Espirito Santo is a solid manager, a likeable guy. But he was sacked by a club that finished lower than us. We also clearly wanted a dozen or so managers before he was even considered.
He can only be seen as a downgrade from Mourinho, however much spin anyone tries to put on it. I think he'll end up as a stop-gap. A manager we'll have for a couple of seasons at most until some better one's are available down the line. We won't really excel under him, neither will be get considerably worse.
After failing on our targets he was a safe option. A steady Eddy. Nothing more, nothing less.