You rarely see prospects like him nowadays. He plays a lot like Blake Wheeler, or a bit like Mark Stone as well but with more grit. He takes the puck right to the net every single time and will make other teams take penalties. His biggest asset is his vision, he's got excellent vision and passing ability. His shot is very good, not like Matthews for example, but he has a sneaky quick release and can get it in tight areas. I think he's a bit like Stone in this area, he has a sneaky shot with high precision and will score 25 goals a year but isn't the guy that will score 40+. His puck protection skills are very good and he's good off the cycle.
Bottom line is he knows what to do and where to be to make things happen and he's willing to do whatever it takes to make plays happen. He's very exciting to watch from a fan perspective. He's the type of player that might not score 100 points a year but people will go see games to watch him play and opposing teams will absolutely hate to play against him and fans from other teams will despise him.
It's still very very early, but I understand why the Sens took him. I think Zadina would also have been a good pick, they are different players that both bring value in different ways. Seeing Tkachuk is very encouraging. Also from what I've seen Kotkaniemi looks extremely polished for his age. I think those 3 will end up being impact players.