Turkish football execs and journos are known to chat a bit of shit. But the long going rumour with Terzic is that he wants to have a go in the Premier League so there could be something to this.
As for him as a person. He seems like a good dude based on most accounts. A Dortmund lifer who went from the stands to the coaching bench. He's had a ton of jobs for them. He's been a scout, an assistant (and reportedly Jadon Sancho's baby sitter), interim manager, technical director, and finally manager. He's good at developing younger players (a must at Dortmund) and plays a direct attacking brand of football, but with more of a defensive identity than Ange for comparison's sake.
He had Dortmund the closest that they've come to dethroning Bayern since Klopp.
Is there a guarantee that he'd be a success here? Maybe not. But he's a young but experienced manager with a lot of upside. And if Spurs want to focus on buying young I think that he's as close to ideal as we can find.