He's alright, tbh. I've watched plenty of both him and Bentancur (my opinion on him is in his thread) over the years.
Back when he was at Parma on loan, he was a weirdly dangerous player - the best way I can describe him.
Weirdly dangerous, because he didn't look like he was all that threatening - he had a tendency to stumble over the ball, look a bit ungainly, and struggle to control it in tight spaces. But, at the same time, he had an ability to cut inside from his nominal positions out on the wide-right and play a defence-splitting pass to an onrushing forward, or drop a shoulder and burn past a player with surprising agility.
Allied with his ability to defend, press and win the ball back high up, it made him a uniquely dangerous player for Parma's system, which was *very* based on lightning transitions from back to front with a minimum of passes and buildup.
At Juve, though, all those negatives (ungainliness, struggles with ball control when under pressure/in tight spaces, indecisiveness, etc.) came to the fore, and he never really showed that agility and inventiveness that marked him at Parma.
So, he's a bit of a weird jumble of attributes. I'd say the conditions he'll play in at Spurs are more similar to the ones Juve face than the ones Parma faced - packed defenses, high pressing and a need for intricacy. Which may not be to his benefit.
But at the same time, he's got so many things that make him potentially good in a Conte system - physicality, a hard worker, defending ability, speed over long distances (not acceleration, but pace, I suppose), and the ability to play those dangerous passes into space quickly.
You can see above the reason why I called him weirdly dangerous - those are not typical attributes for a right-winger (where he usually played), or a CAM (which is where I think his best position lies).
Paratici has loved him for a long time - brought him to Juve in a deal many called overpriced, and we are now buying him for more than what Juve paid for him after two disappointing seasons (staggering the payments with this weird loan-to-buy thing Paratici likes). It's clear he sees a lot in him.
But to me, he strikes me as uncannily similar to Alli - he will do well in a system tailored to his strengths, but otherwise, he's a struggle to fit into a side. But I suppose Conte will play him more than Alli, so it's a squad upgrade on the whole.