Hes probably the next big thing to come down the Mane-Keita route. I watched a handful of games (he played in their win vs Napoli for a higher profile one) and seriously like what I see, he's an all action midfielder with world class shooting technique on him, similar to Kroos maybe.
Theres 0% chance of him moving, although I'd say there's no chance for anyone else getting him either. Salzburg have one of if not the best youth setup in Europe (they won the UEFA youth league recently too) and the work their academy staff and first team coaches put in really rivals the very best clubs. Bayern have allegedly sniffed around and thrown a 30m bid including an option to loan him back for a couple years but it was shot down and rightly so, so you can imagine what response a 9m bid will receive