Where do you rank him? He's a Palmeiras legend. He has a great touch: . Only played 9 games for Brazil.
For me, he fits into a category of midfielders that lacked speed/direct threat; Overath, Gerson, Scholes, ADG etc. Most are popular on this forum, except perhaps the man himself. However, they can not touch peak Kaká, Platini, Robson, Netzer etc. Nor would I consider them for any alltime list.
He should be among the ten best attacking mids in Brazil's history. Behind Zico, Rivelino, Kaka, Socrates for sure. Perhaps even the best 5. Personally consider Pele, Zizinho, Rivaldo, Ronaldinho as more of forwards. Problem for Ademir is he was sandwiched between Pele and Rivelino's primes, and he wasn't that adjustable to play on the flanks like Rivelino did in 1970. He has to be the '10'. For that reason he missed out playing in those world cups and the exposure that would have come with it.
V Hanegem was a great midfielder. I'd put him on par with Robson. Robson had more speed and bravery. V Hanegem could do evasive dribbles and hold on to the ball. Both scored a good amount of goals/headers arriving late in the box.