He's probably going to be an average player, better than what we have right now in Lingard/Pereira, but still avgerage. He has good vision and technique, but not even close to Eriksen, Pogba, or KDB level.
Most of his goals are from FK/Penalties and some long shots that frankly any respectable keeper in the PL would save. He isn't super athletic and his tackling skills would make Scholes look like Kante.
There is a reason no clubs bought him last year as Sporting are massively overvaluing him. Based on the risk, i'd pay no more than £35m for what he'll bring as a rotation option with a small chance of being a regular starter for a top 6 side.
Any smart DOF would skip this transfer. It's not a home run and has too many risks for only bringing in an average quality player. But since we have the worst board in top flight football I'm guessing we'll pay £60m for him and in 2yrs we'll be wanting him replaced with someone proper.