Booker is better than Newton. With or without the knee injury. Kelly was predomiately a 3-point shooter - albiet a good one. Booker has shown flashes of finishing at the rim and some defensive ability. Remember Newton was a JC transfer and was two-years older than Booker during their initial OU campaign. If you think about Booker in two years - if he has the Hield/Cousins work ethic - I think you are looking at a potential starter, which Newton really never was. Booker needs to work on his handles and needs to really learn to go left. His shot is really pure, but if he gets a mid-range game he could be deadly on offense.
The real question is where does he fit. Can't beat out Buddy, but I think he could challenge Cousins for minutes / starting role. Wow if Woodard, Cousins, Heild, Booker and Hornbeak are all here two years from now - OU could be incredible on the wings. That kind of talent could take a team on a deep tournament run.